hm.. this is a kinda question that i've been wrestling some time before. I'd say the following: you will never build your career by writing essays. BUT are you going to built your career writing essays? actually, it's the problem of perception. As for me, i perceive essay writers, as people who want just some extra money. Is it bad? i'd say it is not. In addition, you've got no commitments.
If you are interested in high pay - you can visit PENCAMP... the most highly paid job i've ever met. Cannot say about the quality of the company, but it looks nice.