It's fair to say that gambling will always be an activity that doesn't have any certainties and guarantees regarding the outcome at the end of the session especially when it comes to winning, and that's why many of us always recommend only risking small amounts. The fact of the matter is that no matter how confident you are in your choice of decision at the end of the day, confidence is not something that can guarantee victory. This means as you said that anything can happen even if we are very sure of our choice, and the other thing is that betting a small amount will certainly make it easier for us to take responsibility for any results, especially defeat.
Even if gambling doesn't have uncertainties, people will still placing their bet and playing gambling without stops because they thinks that gambling can gives them much money. They will still trying to wins even with more money and don't thinks about how much their lose later. If they can be wise when playing gambling, they will not risks too much money just to chase the wins because they will thinks that their chance to wins will not too big. They will just use the money they can afford to playing gambling because they don't wants to gets big lose from gambling. They only wants to be responsible when playing gambling and that's why they will only use enough money to gambling.