IN short, yes you can make money.
Longer answer, it will depend greatly on your location/town/games/etc...
As others have said, do it for the love of pinball and it is all good. If you are legitimately doing it to make money, then you could make more cash doing almost anything else with your time. I kept track for a short while and time/$$$ invested vs payout was so small I quickly stopped paying attention to the time spent.
The rewards are in meeting new people, sharing pinball with them, and seeing that spark when they figure out 'it"