All of that sounds reasonable. But it also doesn't need to be a reason to find maintaining OSS very draining or unpleasant, as GP put it.
First of all, when a project grows, its core team of maintainers can also grow, so that the maintenance burden can be shared. This is up to the original author(s) to address if they think their workload is a problem.
Secondly, and coming back to the post that started this thread, the comment was "working for free is not fun", implying that if people paid for their work, then it would be "fun". They didn't complain about the amount of work, but about the fact that they weren't financially compensated for it. These are just skewed incentives to have when working on an open source project. It means that they would prioritize support of paying customers over non-paying users, which indirectly also guides the direction of the project, and eventually leads to enshittification and rugpulls, as in MinIO's case.
The approach that actually makes open source projects thrive is to see it as an opportunity to build a community of people who are passionate about a common topic, and deal with the good and the bad aspects as they come. This does mean that you will have annoying and entitled users, which is the case for any project regardless of its license, but it also means that your project will be improved by the community itself, and that the maintenance burden doesn't have to be entirely on your shoulders. Any successful OSS project in history has been managed this way, while those that aren't remain a footnote in some person's GitHub profile, or are forked by people who actually understand open source.
