Pursuing losses is probably one of the easiest mistakes for this, until finally losing all the money and then realizing it if we have made a big mistake.
lol...
This is the most common thing for us gamblers on which we would only seen our mistake when we are already losing money on playing gambling. Worst mistake usually when we lose money and we didnt even heard someone complaining on their winnings,right? That is why we should learn on our past mistake so that we can able to avoid the things we suppose needed to be avoided.