The real reason to use telegram is that it's miles away the best messenging program out there. It's as user friendly as whatsapp while having completely seamless desktop/mobile integration (something whatsapp and signal have failed to do), it only requires a phone number for the initial signup, and generally speaking it has all sorts of cool features and less bullshit than alternatives.
Then there are the little things - you can create multiple accounts and switch seamlessly, you can delete whatever message from whomever for everyone without leaving a trace (if it bothers you just switch to secret chats), all links are listed in each convo, you have pretty much unlimited and unrestricted cloud storage, etc.
Then you have all the gravy like cool tools for groupchat admin, channels, and bots of course. You can order a taxi or search up a book on scihub (bypassing countrywide blocking) with telegram. You can even do bizarre stuff like discover people around you or verify your identity on a service with telegram.
Yeah my texts are probably being read by the FSB. So what? Better that than the NSA, frankly. If I really want secrecy I'll use Tor or Signal.