Matrix where 99.9% of users use matrix .org? Lol, I run a homeserver for 2 years until I realized it was pointless.
I'm not a big fan of telegram either but the UX is unmatched and you can use it with a burner phone and a FOSS client. Sovereign individuals are pragmatic and use the tools that work at any given time without bitching about it.
If TG servers are shutdown that's fine, I won't lose shit. Same if my SimpleX relays go down.
Also most decent FOSS projects only have a telegram support room.