I basically throw every YT video I watch into TubeArchivist. The browser extension makes this a single click. Currently have over 5TB of YT videos saved, including whole channels.
If you don't need to access it much and just want to archive it, tape is probably a contender.
Some consumer drives aren't well suited to continuous use - they're designed and rated for only a few hours a day. Heat and vibration tolerances are lower. I wore out some WD Greens that way - they were throwing errors by 60k hours.
NAS drives are the opposite, they're designed to run 24/7. In the same way, enterprise drives are designed for better vibration tolerance to be crammed in a chassis with many other spinning disks.
Basically they'll work, but longevity is an issue, which is particularly relevant to us hoarders. I use WD Reds in my NAS and enterprise/SAS drives in my servers now. Seems to be a good combination.
Motherboard, CPU and RAM - no problem at all (more accurately, problems are easy to spot with diagnostics and they shouldn't wear out).
Chassis - a bit of a wild card. The backplane in one of my systems is faulty.
PSUs - ideally new.
HDDs - almost all of mine are secondhand. Enterprise- or NAS-grade drives should have many years of life left. Ideally buy new to benefit from warranty but my experience has been great.
SSDs - nope. Buy new. I bought some secondhand Samsung SSDs and they developed problems, both threw IO errors after a few weeks. SSDs are cheap enough not to bother with secondhand.
Everything else I bought used, including the rack. In fact, the only things I bought new in my entire homelab are my router and WiFi AP.