Whats are pros of XMPP?

Pros of XMPP is that I can fully self host it, it can do video & audio calls too, and has good clients that aren't just a webpage wrapped in Blink (aka, Electron). Matrix is a pain in the ass to self host, especially if I don't want to federate. My XMPP server is private, friends & family can use it, and that's it. That's what I needed, and it delivered perfectly. It does End-to-End encryption. It is weaker than Signal, for sure, but it's enough for what I need it for. In short: it's reasonably simple to self host, has good, usable clients for both platforms I care about (Linux & Android), we can chat, we can have group chats, we can have audio & video calls.

Also could u tell me about self hosting cost and time you spend on it?

Well, I've been self-hosting since about 1998, so the time I spend on it nowadays is very little. One of my servers has been running for ~4 years without any significant change. I upgrade it once in a while, tweak my spam filters once a week or so, and go my merry way. I haven't rebooted it in... checks uptime 983 days. Maybe I should. My other, newer server, is only about a year old - it took a LOT of time to set that up, and the first few months required a lot of time. But that was because I switched from Debian to NixOS, and had to figure out a lot of stuff. Nowadays, I run just sys update && just sys deploy (at home, on my desktop pc), and both my tiny VPS and my homelab is upgraded. I do tweak it from time to time - because I want to, and I enjoy doing so. I don't have to. Strictly necessary maintenance time is about an hour a week if I try to be a good sysadmin, ~10-15 minutes otherwise. It Just Works™.

As for costs: my setup is... complicated. I have a 2014-era Mac Mini in my home office, which hosts half my self-hosted things (Miniflux, Atuin server, EteBase, Grafana, Prometheus, ntfy, readeck, vaultwarden, victorialogs, and postgres to serve as a database for many of these). It's power consumption is inconsequential, and the network traffic is negligible too - in a large part because I'm the primary user of it anyway. It is not connected to the public internet directly, however: I have an €5/month tiny VPS I rented from Hetzner, that fronts for it. The VPS runs WireGuard, and fronts the services on the Mac Mini through Caddy. iocaine takes care of the scrapers and other web-based annoyances (so hardly anything reaches my backend), unbound provides a resolver for my infra, vector ferries select logs from the VPS to VictoriaLogs in my homelab, and I'm running HAProxy to front for stuff Caddy isn't good for (ie, anything other than http).

Oh, yeah, I forgot... we have poweroutages here every once in a while, so I have to turn the mac mini back on once a month or so. It happens so rarely that I didn't set up proper Clang + Tavis-based LUKS unlocking, so I have to plug a monitor and a keyboard in. It didn't reach a level of annoying to make me address it properly.

A bunch of my other services (GoToSocial, Forgejo + Forgejo runner, Minio [to be replaced with SeaweedFS or Garage], and my email) are still on an old server, because the mac mini doesn't have enough juice to run them along with everything else it is already running. I plan to buy a refurbished ThinkCentre or similar, and host these in my homelab too. That's going to be a notable up front cost, but as I plan to run the same thing for a decade, it will be a lot cheaper than paying for a similarly sized VPS for 10 years. The expensive part of this is storage (I have a lot of Stuff™), but only comparatively.

By far the most expensive part of my self-hosting are backups. I like to have at least two backups (so three copies total, including the original) of important things, and that's not cheap - I have a lot of data to backup (granted, that includes my music, photo & media library, both of which are large).