I've done it, but it's recommended you have a separate incubator for this because with some diseases, the chicks can hatch with them, and you don't want to contaminate your incubator. Although if you did a deep clean between each hatch you'd probably be fine. I charged a dollar an egg, and I did okay with it because I hatched mostly for people I knew, but I also put an ad on craigslist and got few bites, but nothing panned out. As a person hatching for someone, you also have to be responsible. I had a friend give eggs to someone to hatch for her so she could sell chicks to a woman who desperately wanted marans, and the person who she gave the eggs to, who we knew from a forum and had actually met with before, took the eggs, never paid my friend, hatched the chicks, claimed her car was broken down and she couldn't get them to the other person, and basically stole the chicks for her and her neighbor. I had to hatch eggs for my friend after that so the poor lady who was supposed to get the chicks could have them. I've also had chicks dumped on me after hatching for a person and never picked up. So you have to be aware some people may be skeptical of you and that you may end up stuck with all the chicks you hatch, so these are things you'll have to prepare for.