The ability to control emotions is good to minimize the possible bad effect of gambling but it will not help us to have bigger chance to make money from gambling. There is no guarantee in gambling, whoever we are, how patient we are, how good our emotion control, how good our bankroll because Luck does not care about all these things. No body knows when the luck come, to whom the luck come, and how the luck come because it is like a mystery that we will never able to predict.
Controlling emotions can save us from big losses and it may also help us to hold our winning but if we loss control of our emotions then we may fall into big loss and may not gather any earnings from gambling that's why controlling emotions is very important for us.