There are a lot of Telegrams that have blown out of proportion and just seem to be a method of the creator/admins to advertise some fake coin alongside their bot which spams airdrops.
There's one i'm following currently that has 17k members that consists of no spam/bots; fortunately - take a look:
https://bitcointalk.org/index.php?topic=2937292It's for a digital advertising project: Ternio