Being a hobby operator as well - I have to agree with everything Whysnow said above. Do it because you want to do it. I really enjoy introducing and reintroducing people to pinball. That's truly the best part of it for me. Well, that and having a public location to go to and play pinball at! A few other things I'd like to add.
When putting out games, be sure they're tested thoroughly. Something that's OK at home (say...a ball that hangs once in a while) isn't gonna fly on route. You'll get tired of stopping out to fix that sort of thing real quick.
Don't get attached to the games. They WILL get played, so expect things to break / wear. You could have food/drink get slopped on them. A rubber will break, and someone will think it's "funny" to keep playing it to try to break something else. Just know that the general public will treat them rougher than you would, and be OK with it. Keep them clean, waxed and fully functioning with regular maintenance. If you take pride in a well playing game, others WILL notice it and over time come to appreciate it! Expect to have to stop in at LEAST 2-3 times a week, and be ready to get calls until bar time!
LEDs are your friend. Keeping the heat down really saves on melted plastics, inserts and connectors.
DBV is a must whenever possible, and like others have said be sure to get the highest split possible.
It's a lot of work to not make money, but it really is fun and rewarding in it's own unique way. If you decide to do it - I hope things go well for you!