Well first off Telegram doesn't actually do end to end encryption unless you manually opt in. They don't allow end to end encrypted voice or video calls. They don't allow end to end encrypted group chats. Telegram is also a for-profit company that has no guarantees that they'll continue to not harvest your data because they're a pre-profit startup company.
1. e2e chats are not default, and they are clear on this fact. It is very easy to start one, though.
2. All voice and video calls are e2e encrypted. [1]
3. They do not harvest your data, and they are not for-profit. All of the money invested so far has been put up by the founder, Pavel Durov, [2], but they have outlined possible methods for financing. [3]
What are those random emojis in voice calls for, then? I assume (warning: assumption) the voice calls are actually encrypted, even if it's with keys received from the server and opportunistic unless you verify the emojis for a particular call. (Video I don't know, and group chats and most 1:1 chats are definitely plaintext yeah.)
WebRTC mandates end-to-end encryption, but that's for the web browsers. Can you please link me to evidence that Telegram does not have any way to encrypt video or audio calls?
You say Telegram is a for-profit company, but I am not sure how Telegram makes money, at all. It was approached by various government agencies looking for backdoors and claims to have rebuffed them all. Unless the whole thing with the founder of vkontakte having to give up his shares to mail.ru and run, was staged, I'm pretty sure he's an anarcho-capitalist who isn't very happy with states having data. So if that's the case, Telegram (unlike Moxie Marlinspike and Jan Koum) is much less likely to sell out their platform down the line.
