That doesn't really have anything to do with GP, right?
I feel like this is a maybe-true comment on the link in general, but not the post you're replying to: entitlement/general nastiness towards open source maintainers is very common, as is the misconception about their degrees of commitment to their projects. That's true whether or not a project switches to a paid model, and whether or not maintainers post what you refer to as "lectures".