I've been writing on various sites on the web for 22 years. I've forgotten more writing sites than I can remember. In general, only the top 5% earn. I've still to figure out whether the sites are weighted like that, so that the site is profitable.

Writing sites on the web are not for the benefit of the writers. They're an easy profit-making source for people who want to make a lot of money out of other people who think it's easy to write, and who are encouraged to pay money in order to learn how. It's an enormous market, and as writers have been conditioned not to accept payment, they are at the losing end.