Occasionally on Upwork you get lucky and land a good project. But if you're a good developer expecting more than $30/hr you will never be able to stay busy even part time (more like a couple projects a year).
I've heard services force you to compete on price and drive rates down but I suppose it's worth a shot.
That is possible. But I do freelance writing for a service I really like. My experience convinces me that it is not inevitable that it go that way. I hope that someday I can spell out some best practices for how to set up a good service that doesn't go that way.