First of all gambling is itself a unsafe method of earning. And how can it be safe. Yes undoubtedly you are to be lucky while
gambling and playing with the brain is the most.
safe method : play-profit-run !
Apparently that doesn't happen to most people. You made it sound like it's an easy thing to do and there's no risk involved.
Play - Yep, no risk at all. You just have to bet your money into something.
Profit - Nope, you don't know if you're going to profit at all. It's either you profit or you lose all the money that you have put at risk.
Run - It's actually depending on your discipline. If you don't have control on yourself, then I doubt you can run once you have some profit. If you won some, you'll get the feeling that you want to bet more. But if you lose, you have no choice but to go home.