It’s just that only a very tiny fraction becomes popular. That’s when the problems start. Some may see their software being adopted by millions and may start feeling envious of those that make money using it.
Maybe unpopular opinion here, but I don’t see why they should get sponsored by a company. They made the software open source for a reason, and others used it based on the terms it was licensed. No foul play here.
On the other hand it’s well within their rights to ask for money to continue supporting it and developing it. Just because they made something open source in the past doesn’t mean they signed up to be forced to support and develop it indefinitely.