Seems sad to be them but this has always been the case with open source. There has been countless successful businesses established that run with on source software (think Linux, glibc, etc) and almost none of them payed back open source developers or contributed anything.
To say that developers/authors of open-source believe that if their projects get picked up by some big company they would also be payed seems silly and childish. This has never been the case, why would they even believe that? It was rare when a company payed open source devs for their work (and it made the news, like when RedHat gifted Torvalds a lot of stock before going public and it's not like Torvalds was the only kernel dev at that time).
To say that developers/authors of open-source believe that if their projects get picked up by some big company they would also be payed seems silly and childish. This has never been the case, why would they even believe that? It was rare when a company payed open source devs for their work (and it made the news, like when RedHat gifted Torvalds a lot of stock before going public and it's not like Torvalds was the only kernel dev at that time).