What story teller wanted to say?
OP meant that if you are a fearless gambler, your chances of winning are higher as opposed to a person who do not take big risk in gambling. Although I somewhat agree that you should have appositive mode when you play gambling and should have belief in yourself that you will win but again sometimes the luck even do not help the brave too. It will also make you lose big if you take more risky moves.
Being bold doesn't guaranty you a win, you still have to take a chance, even if you take the game in a calculated way, the chances are still there that you are going to lose, but big bettors can always extend their bet until they reach the win that they want, one of the cases is the martingale method, where doubling your bet for every lost as long as you have funds or can add.