Because Telegram's TON was a huge success, yeah,
- $1.7B raised in ICO: This is far more than has ever been raised in any other ICO. I also think it says something about investor optimism. I'd bet that this was a data point in Facebook's decision to do something similar with WhatsApp.
- Telegram's development team: Some of the best in the world. They've done a lot with a few highly talented programmers and mathematicians.
- 200,000,000+ monthly active users as of March 2018.
> development team: Some of the best in the world
Well, messaging isn't exactly rocket science.
And they did a lot right (open source clients, bots, channels, proxies). But their secret chat implementation is weird (literally every crypto expert has the same question: "why did you pick these extremely unpopular barely known primitives to reinvent your wheel?")