Several years ago I was looking for something to use as a family chat server. Many of my friends/coworkers were using Slack/etc., but since my immediate family members didn't already have a preferred chat app, I was hoping to self-host something open-source. Matrix was under very active development at the time and I was pretty excited about the prospect of using it. Matrix didn't even have E2EE yet (I think it was under development), and that really wasn't a feature I needed or cared about (disappointing to read about all the trade-offs involved in this post though). The computational/storage costs for Matrix really were way too burdensome though. I ended up going with Jabber (Snikket). A jabber server costs essentially nothing to run. Highly recommend.