Well, so far I am quite content with the sales of my essays.
Of course, there are only a limited number of people who take interest in academic topics. On the other hand, this highly depends on the area of study.
A German friend of mine, who got me into the whole topic, has successfully published a thesis on social media strategies and online marketing through this site. Works well for him.
It couldn't possibly harm, I guess. Also GRIN seems to have a strict anti-plagiarism policy.