In the early 1990s, to keep people waiting in line to play poker happy, Los Angeles' Commerce Casino had a brilliant idea: put pinball machines in the waiting room!
In a room full of gamblers, naturally it wasn't long that people began betting on pinball games. Here's a fascinating story at Kuro5hin about how a guy who made a lot of money playing (and betting on) pinball:
That day, I took in over $20,000, starting with just $2,000 in my pocket. I started making simple prop bets for $100 and $200, and soon I became more aggressive. I was astounded at how easily these guys would take bets - even things they knew couldn't possibly be in their favor! It was as if they were gambling, pulling the handle of the slot machine, and that they didn't have any expectation to win.
Within a week, I had built my bankroll up to $50,000. I was playing pinball 10 hours per day and I wasn't the least bit fatigued. It seemed I rarely lost a prop bet (like all gamblers, I kept professional records, of course, but I have been unable to find them. I imagine I enjoyed a 20% edge over most players though).
That week, I took 5 days off and celebrated my successes with a trip to San Fransisco. I was living like a king, drinking $1,000 champagne in an equally expensive hotel room. I had no reason to believe anything would change in the future, and I looked to be a millionaire in no time.
But turned out it wasn't that easy: Link