Telegram has a lot of pros, but it can be safe only as long as you and every person in your circle sets it as such. Chats are not encrypted by default, you have to set it in group settings. Your phone number isn't hidden by default, you have to manually set its visibility to "Nobody".
It even asks to let it pull your contacts, Facebook-style. There might be several such gimmicks, but generally they are easy to notice and control.
The biggest advantage(?) Telegram has is that everything is saved server-side instead of your phone. So you don't need to keep having to back up your chats and be scared of losing everything if you lost your phone.
There is an standard client-server encryption in Telegram. If you want e2e encrypted chat, then use Secret chats. Almost all messengers nowadays use client server encryption. So the biggest problem is not man-in-the-middle attack, but physical access to device by someone and malware installed via breaches.
@caglel@people_are_cute The standard encryption is utter trash. First, they never needed to make it. Ever. Second, it was audited and laughed at by everyone. Third, even after they fixed the issues, it's still laughed at by everyone.
Pulling your contacts lets it get a pretty good fingerprint of who you are, from who you talk to. It can already get that from who you actually message, but it's getting a lot more information about you from pulling the whole list and not just who you talk to through telegram.
I understand, but if you are new to this conversation app, right after installing it would be good to know which of your contacts your are able to talk to there. I don't see asking one by one and adding them manually a good solution, maybe there is another one I don't see
You were calling someone cringe for asking why Telegram isn't secure. Now here you are thinking your Signal messages aren't sitting in an NSA server somewhere in front of all these people. You're delusional, mate. You're like a step above a script kiddy in regards to technical understanding. You're so close to understanding the reality that you have no data privacy, but you're still so far...
How does it stay on your device? I'm notified if a contact of mine uses signal. That means if someone has my.number in their phone signal will let them know I use signal. I don't really want someone to be able to confirm that I use a service.