~snip~
Unfortunately, our brains are wired in a way that if you've took some action and got desired result (positive feedback loop), you'll feel the urge to do it again. So if someone had the discipline to stop betting in the right time and walked away with profit - they're likely to return and try to repeat that success.
Gambling perfectly exploits psychological flaws.
That is true.
Our brains are always trying to explain things however they can, even if it doesn't make sense.
For example, if you happen to experience two rare independent events at the same time, your brain will think they are correlated somehow even though it was just a coincidence. This explains some of the "bad luck" tales like a black cat crossing or superstitions in general. The brain thinks "Something happened at the same time that something bad happened, so they must be correlated", but it's just a coincidence.