I wouldn't do this for a variety of reasons:
1. The essays that you pay for are usually absolutely ****. I saw an essay online and it had not at all been proof read with no citations. These people writing them don't care about plagiarism as long as they get the money so the essay would be flagged very quickly. The person who usually marks your work could also see it's not written by you.
2. If you want something to be high quality, then you'll do a much better job than anyone else anyway. Continuing on from the first point, the quality will not be as good as if you did it, because you're the only one who cares about your own grades.
3. I could not apply for a degree level job knowing that part of the degree wasn't even done by me and I may have not actually learned every single part of it so I would feel like I didn't deserve it!
3.1 I couldn't look my own family in the eye when they're celebrating my achievement, whilst in the back of my mind, I knew I cheated. It would bring nothing but bad thoughts when thinking about my degree. You will have positive thoughts of it if you know you worked and have done it all yourself.