Especially in the age of AI tools, I also thought about this a few times. The current idea I have is something like a parking meter. Every expensive transaction (like calling a model) would subtract from the money pool, and every visitor could see how much is still left in the pool. In addition, a list of the top 5 donors with their amounts might improve the group dynamic (like on pay-what-you-want pages like humblebundle.com).

It would be more about covering the cost than about making someone rich, but I think that is what most of the people who build stuff care about. Sadly, I don't know a service yet that offers this model.