I’m from Mexico, and the most used chat application is WhatsApp. It’s used for EVERYTHING. I use Telegram only for contacting my family members (both my parents and my brother). They also use it only for this family chat. All my (and their) contacts use WhatsApp instead.
Now with the news that Telegram will collaborate with Twitter, I feel that I should delete it. Not that Zuck is any better than Musk, but still…
Also I don’t think it’s worth the effort to teach my parents yet another messaging app, like signal.
End to end encrypted doesn’t mean they don’t potentially store a copy of the keys somewhere. With proprietary software, you never know what it’s actually doing since you can’t verify the code does what it says on the tin.