[eTomte]

It might be expensive for an organization to host, but for individual / small groups it can be as low as $6/mo. I've been running a small Matrix server on a DigitalOcean droplet for years now, and the $6/mo plan has been working fine for 5 users, and three bridges running on that server.

[toastal]

I believe all messages/multimedia from all users & the history all the rooms & private messages need to be mirrored which can end up being a lot even with a few users depending on what they’ve joined. If my understand is wrong tho, I’d like to know so I’m not running around with this notion.

[eTomte]

No, you're right...that can be an issue. I had to configure my server to disallow large rooms and enforce some file size limits.