But they don't seem to advertise and very few people know it's a really good option (with phone apps to replace the cloud ones, even).
It's very cheap to run self-hosted these days even on your own HW. 1GB/20GB VMs cost $1-$2 per month.
Really, this should be an age of self-hosted if the cost was ever a limit.
But it's possible to run all kinds of other stuff, if you know how. All kinds of scratch your itch apps, monitoring, backup, small web apps, file sharing, audio server, seedbox, databases, etc. Stuff you'd not find a service for, because it violates copyright when it's not done for personal use, etc.
It's especially useful if there are multiple people in the household.
Most of what you list are or can be one-time costs. And most of it can be automated in a run-a-script, check for errors and forget about it in 1 minute, or deal with some failure in 15minutes.
The main benefit of running your own is that there are almost no ongoing costs. Lot's of the SaaS prices are really overblown, so running your own is appealing there.
And people spend time and stress on dealing with SaaS issues too from time to time, so it's not like you just pay and use without any additional costs.
It just needs a serious consideration.
Also running your own can be fun/fulfilling in its own way, because you now have more control and you're allowed more creativity. For some people that may ba a benefit too.
You can can indeed improve privacy, but it normally means giving up speed (like Tor).
Additionally, there are other issues of p2p as a main solution. For example, phone battery or often being blocked in routers of public spaces etc.
I think that a mix between Fediverse and P2P would be nice.
A power user can choose to be a node, knowing the price. But the common user would use some server/service to access it. But those must be planned such that switching is easy.