Earlier quoted context omitted.
Because matrix (the open source protocol) is federated, you have options: matrix server (for self-hosting), SDKs, bots, libraries, etc. = https://matrix.org/docs/projects/try-matrix-now matrix clients = https://matrix.org/clients/ matrix bridges (to interoperate between matrix and other services like irc, slack, telegram, etc.) = https://matrix.org/bridges/ if you don't want to manage on your own, and simply want to…
How many users does matrix have? I tried it last fall on 2 different servers. (Hosting an own server is not possible on a small root server you can get for 5 EUR/USD a month, it requires signifcant resources.) My experience was a bit disappointing. It seems pretty overloaded already, especially the irc bridge. And we are talking of thousands of users. I'm pretty convinced that with millions signing up it would collap…
I'm no longer hosting my own homeserver (can;t spare admin time for it), but when i did, it was running nicely on a $10 USD/month on digital Ocean...and this was circa 2019...I'm not an expert but as i understand it, both synapse (the python-based reference homeserver), and the vastly more performant (though beta) Dendrite have significantly improved since back then. There is certainly something to be said if you're high profile folks (like @Arathorn) who are members of tons of rooms...one can imagine that it would require more resources to support such vastly high interactions (for room data history sync, etc.)...But, hey, its early days, if the experience is too raw for you, you can wait a little while until this becomes more mainstream; no harm, no foul. :-)