[JaimeThompson]

Telegram has, as far as I know, no revenue model at all so they most likely are mining the heck out of the users and what they post.

[tazjin]

Telegram has ads as of a few months ago, because Durov can't personally fund it anymore at its current size.

https://promote.telegram.org/

[JaimeThompson]

I haven't seen a single ad at all for some reason in the multiple groups I am in.

[frollo]

At the moment, ads are only displayed in public channels with at least 1.000 users, so they are still pretty rare to come by (like, I use Telegram regularly and only see them every other day). Plus, I've heard that some clients aren't supporting them yet (even if Telegram's stance is that every client should), so maybe you'll never see them.