I did not understand how a gambler can be sure before gambling that he will win. If this could be confirmed in advance, then no gambler would have lost money or someone who knew this would have invested all his money in gambling and would have borrowed money from his neighbors or relatives and gambled. From what I understand about gambling, I can at least say that in the case of gambling, nothing can be said for sure in advance about the outcome. Maybe a gambler can make a prediction about the outcome of a gambling game through his skills and experience, but no one can give a guarantee that that prediction will be 100% true.
Similarly, when a gambler bets, there will be two opponents in the case of betting, but that gambler will definitely bet on one opponent's site and the opponent is stronger. When betting on a site with a strong opponent, he will feel that his chances of winning are high, but he will never feel that he will definitely win.
Actually there is no promise for anyone to win while staking, even when you have insane level of skills or exposure to, randomness is always there that put an end to any certainty. That is why I believe that luck is still the boss & prediction can never award 100% reliability even if it is construct on knowledge.
See, smart betting has nothing to do with sureness however it is just about the capability to manage the risk. there are these emotional biases such as the fantasy of control or the gambler fallacy that actually twist our brainpower & make us feel more believing in oneself than we really are. Sure you could double up skills however fate always has the last word, no cap