Which distribution should I recommend to beginners to scare them?

Gentoo obviously :
To install, easy just get this iso, with no GUI, then whip your hard drive, create partition, copy the Linux core, config your core based on the hardware technical details of every components you have and will use, compile it, add extra core drivers, compile them, add all the software you'll use to get a GUI (Desktop environment), compile them,. Now you can finally restart without usb stick! Add all the software, configure and compile them. And for every update of every software you may check the details to be sure it doesn't break your config.
Easy no? It just took you a month to get all the steps right!

Ya there's Arch. There's NixOS. There's still Slackware.
But have you heard of 9front?
9front is useless. You won't be gaming or working with it.
Mostly, you'd learn how operating systems are constructed.
Or DoomOS or DoomLinux. It's a basic linux system where DOOM is the shell.
I forked this and tried to get it running. Learned some interesting things. Still doesn't work for me. :]
https://github.com/fl64/DoomLinux

Hannah Montana Linux or Biebian

Brodie's beard is pretty yikes in this picture

Is that a really young Brodie Robertson on the right??
- I took picture from https://brodierobertson.xyz/ idk is this fake site or not
- Honestly, I can't tell if it's not an anime girl avatar anymore.

LFS

No grey in beard? Shame 🤓

NixOS

Arch is fine... It has good documentation.
NixOS or Gentoo is probably my pick.
- Or Linux from scratch

To scare them? Windows.

It's the absolute best way to make someone become a Linux user for life.:-)

The nixOS slander in these comments would be valid if nixOS were simply a distro and not a cult…
- that's absurd. cults kill people, and we only ruin marriages.

NixOS:
Gentoo:

When I was first looking into Linux I asked the only friend I knew who used it and he unironically recommended me Arch...
A year later I actually gave Arch a try, but by then he apparently hated Arch and switched to Gentoo and I stopped asking him for advice at that point.
- he apparently hated Arch and switched to Gentoo
- I have been using Arch for a half a decade at this point and its worked out well for me. I like how its very stable despite being bleeding edge (relatively speaking). It's made gaming a lot easier, and I was pleasantly surprised when Valve announced SteamOS was switching to it as a base.
  A lot of people have varying levels of purism when it comes to linux, and it sounds like your friend dipped his toes in with Arch and realized "not pure enough" and then jumped in on the deep end with Gentoo. At the end of the day, Linux is Linux no matter which distro you pick, but each distro highlights different strengths and weaknesses of it. Its all about the package managers, the repository contents, and the maintainers. Occasionally, technical support might matter.
  So, pick whichever distro you like, move around a bit to see what has the least papercuts for you, and then stick with that until you can't anymore.
  
  very stable despite being bleeding edge
  Try testing. And be just as amazed as me on how stable even that is. It literally runs on my main server. The one that, if it goes down, everything of me is down. Yet, I never had problems, for years.
- I switched from Arch to Gentoo, for me it's just the next step of taking advantage of every last bit of my hardware. But unless you are seriously invested, I would never recommend Gentoo to someone. If you just want something that's up to date, go with Fedora. If you have some spare time, go with Arch. If you have no hobbies at all, go with Gentoo.
  
  I dunno, apart from compile times, Gentoo is the simplest distribution ever. I have way more problems with my Arch or Ubuntu (Neon) installations.

Neither existed when I installed Linux the first time.
- When was this? Arch Linux was initially released in 2002, about a year before I tried knoppix for the first time.
  What was your first distro, unless you used Linux before distros, if so what was your first installation experience like?
  
  Around '97, playing with MKLinux.

Who TF is scared by Mint?
Did a clean upgrade/install of Mint about 10 hours ago. I'm back to business as usual. Minor tweaks, no tinkering.
- I installed mint, and my Linux knowledge (little to none) plateaued because it never breaks. I never have to fix anything. I'm the iPad kid of Linux.
  
  How dare it work!

Don't? Arch is less scary and more annoying.

gnu guix?

https://archiveos.org/hannah-montana/
- It has been created to “attract young users to Linux”.
  Might want to update their "kids these days love this" reference list a bit 😄
- I thought that was the ONLY distro...?!

NixOS: How do I install OBS?
edit /etc/nixos/configuration.nix
locate environment.systemPackages = with pkgs; [
and add

linuxPackages.v4l2loopback (wrapOBS { plugins = with pkgs.obs-studio-plugins; [ obs-backgroundremoval obs-shaderfilter obs-vintage-filter ]; })
Then you need to install the kernel driver
you can find the instructions here:
https://nixos.wiki/wiki/OBS_Studio
make sure you follow the part about boot.extraModulePackages = with config.boot.kernelPackages; [ v4l2loopback ];
if you want to use the virtual cam driver.
You may find out that you want to install this in home-manager or flakes instead, but those are novels themselves.
edit: ohh yeah almost forgot run
sudo nixos-rebuild switch
after you edit the configs to install
NixOS: How do I update the version of OBS after it's installed?
sudo nix-channel --update
sudo nixos-rebuild switch
If it breaks, the errors are mostly unhelpful, you need to poke around and make educated guesses.
If it bricks you can go back to the previous version in grub by selecting the second to the top entry
make sure you garbage collect every now and then or the app store gets huge.
- I've been using Linux for nearly 30 years and I recently noped out of NixOS. It's a great concept, but I'm old and I don't want to spend the rest of my days configuring stuff just to get to where I would be in 30 minutes on a less rigorously designed distro.
  
  That is, until your distro releases an update and you're like "what do you mean the update failed? So does that mean the update script rolled the changes back?" and then you find out your entire system is in a half updated state and you need to clean install
- Came here to say NixOS too. The idea behind it is neat but the implementation is the most obtuse Rube Goldberg machine I can imagine.
  
  For me, it felt like old times. Bringing up slackware, then bringing up redhat, then fighting in laptop Nvidia and AMD drivers. I was scary how much of my existing knowledge was useless though. If you install it by the book, you can't even run a linked library.
  I spent a couple of hundred hours learning how to configure it. I've been running it for around a year and a half. I'm still sub-par. First time around, 23.11, I installed home-manager as a flake. I got it up and running in a couple of hours, but managed to wedge myself when it was time for updates. I had written just enough weird nix language to make my configs not work in 24.05. I could get the OS to come up, but not home-manager. I started fresh, taking old configs item by item and re-implemented them via the docs fresh.
  When I got a new laptop, I booted off the USB, copied my home folder and grabbed configuration.nix and home.nix and it all just magically worked.
  That said, NGL, 25.05 has me a bit worried :) But at least I don't have to fight Wayland this time.
- It's actually easier than that, but I know what you mean. Yesterday I installed arch on a new laptop, after two years of NixOS. I think I might swich the desktop too.

Slackware still exists, if they survive they'll be nigh immortal.
- slackware
  <graybeard> Way back when, in the bad old days of ISA cards and IRQ collisions and who knows what "90% soundblaster compatible" means, slackware had amazing install images. you had some dusty old 386 with 5 1/4" drives? Oh and you added an ISA SCSI card so you could use one of those new fangled ZIP drives? Yep...just look thru the ftp site and I bet you'd find what you needed.
  Mind you, still had to write all of your own /etc/init.d scripts, and every other config file under the sun, but you could get almost any machine up and running before all them fancy new modular kernel drivers came into existence.
  </graybeard>
- Can confirm. Been living for far too long at this point

Nyarch

Since people fear parentheses, GNU Guix.
- Man, i'm a NixOS user so probably also biased because i got used to the nix language, but legitimately all the parentheses in guix confuse the hell out of me lol

I honestly don't think Arch is that bad or complicated. It's just that you have to go into it knowing that you're in for some reading, tinkering and following step by step instructions along the way. I'd start with something like Mint or Ubuntu for a first look for sure. But once you're ready to learn a bit more about how the Linux system works and is put together, Arch would straight up be my first recommendation. Even if it's something you play with on the side in a virtual machine, for me at least, starting on Arch was when my Linux experience went from clicking at things and copy pasting commands into the terminal to still copying and pasting commands lol, but actually learning why and how and what too.

Great, now I've got the phonk walk in my head

I'm planning to go Arch on my secondary that had popos on it. I've only used mint and Ubuntu before.

Mint is goat
Remember to make a backup pipeline with Timeshift and you’ll be fine

Puppy.

I vote for LFS and maybe Guix