I guess the first thing all people needed to do is self-hosting (Yunohost, Nextbox, or the like), and the second thing is paying for Open Source software they use (if they can pay, as digital communication should be free very much like the commons -fresh air, drinking water- but those who can should pay imo.)
Self-hosting is probably more affordable to do when ran out of your own home. I run my lemmy and mastodon servers out of my home on 16GB of RAM and 300MB of storage space. This would cost a small fortune to pay a cloud hosting provider for.
Self hosted at home really depends on what sort of Internet you can even get. You might be metered, you might only have a couple mbps upstream, it probably is against TOS.
It's definitely against the ToS for me ISP. I doubt they'll ever really find out because the bandwidth I'm using isn't as crazy as the other customers which regularly stream from Netflix, Hulu, etc. I can kind of hide in plain sight. Also, my internet connection is fiber to the home. I have the lowest tier of service at 300MiB up and down. So I guess I realize I'm coming from a situation of relative privilege. I wish most people had this capability.
If you mean cloud as in EC2 or it's ilk, probably. But in a case where scalability isn't as much of a concern, an appropriately spec'd server can be quite affordable on KimSufi/SYS (maybe 30/month?)
My server in my home costs me a lot less than 30/month to operate. Since this is a hobby for me I don't assign a monetary value to the time I spend working on it. I built the server with second hand components that I got at a swap meet for less than 700 dollars. Now knock on wood things have been running smoothly and I do a lot with this server. It doesn't just power Lemmy and Mastodon, but it also does my Jellyfin and NAS. It's probably overspec'd for my needs but that means I can use it for a long while.
Depending on the provider, you can get 16GB or 96GB of RAM for less than $50/month on bare metal, which includes repairs, power, and a 1Gbps unmetered connection. Pure cloud tends to be more expensive.
I pay far less than that in actual utility usage to operate my server which has 128GB of RAM and 16TB of storage space. I've just allocated 300GB of that for Mastodon and 300GB for Lemmy for now.
There is, for a lot of people, a fairly large amount of value in never having to worry about hardware dying. If it does, that's someone else's problem, and it will be fixed, as far as you are concerned, rapidly and without any interaction with you.
How much any given person values that is going to vary wildly, but it means that you don't risk having stuff go down at a moment when you can't do anything about it. Maybe you're on vacation, and you don't have any hands that can do anything. Maybe you're sick, or just extremely busy that week.
You're not wrong that this comes at a fairly substantial monetary cost, but it is wrong to say that this isn't, in many cases, a cost that people are more than willing to pay in exchange for the benefit.
I see maintenance as a part of the joy and learning of the hobby, much as a gardener enjoys the hard work of moving heavy bags of soil around. It's all very much up to the individual. Some hobbyists have a deeper passion for it than others and that is perfectly okay.
To be honest, the homelab for me is not completely a cost/benefit analysis. Sure, I'd save money if I calculated my time spent. But for me this is a hobby so I don't put a monetary value on my time spent. Everything I am doing is learning so I am actually getting value from it. The hardware I obtained second hand from a local swap meet. My utilities have gone up much less than the cost of renting a VPS.
I agree there are many forms of contribution (e.g., writing code if you're a developer), it must not necessarily be money, but am not sure whether I understand what you mean.