I mean, I'm not saying that all humans are completely self-interested. I think volunteering in your local community is often a great way to meet some excellent people. And local volunteering contains a lot of the feedback loops that will encourage normal, well adjusted people to participate - you are becoming part of a real social group, a group of friends, who are doing something positive that they can see the results of in their own lives.

And I think the pioneers in early free software had a lot of these same things going for them - they were part of a small, dedicated community, leaving their mark on the world.

But a lot of foss software has been written by people either in non-profits, or in for-profit organizations who finagled their way into getting paid for the work. Eg, Fedora, Ubuntu, and Docker were / are mostly written and maintained by people who are being paid for their work.

I think Red Hat probably shows the best way forward. Write the software as opensource, then sell hosting and support as a service.

And as part of the software they provide, they should also provide an ootb way to ask people for money. Essentially, you could have a fediverse instance that has moderation and (likely at least in the beginning) content creation/aggregation/curation as part of the service. The selling point being that the feed and comments are of so much higher quality that it is worth it to chip in $1/month or whatever to participate.