It is important for a gambler to have confidence. Gamblers easily become overconfident due to a few small successes. Yes, if there is overconfidence, any gambler will face big losses. Because due to overconfidence, there is no time to think wisely. Due to overconfidence, gamblers become arrogant. At such times, it is very natural to make wrong decisions. Apart from being arrogant, gamblers become alcoholics and emotional. They make big bets on emotions and face losses. Therefore, a gambler should be confident, but never overconfident.
In sports betting, the answer is yes since it dictates the amount of risk someone willing to take on their bet based on their confidence to their bet.
Sports betting is skill based so you can gauge your confidence depending on your analysis skills unless someone is too naive to determine what is an accuracy over just self speculation on their bet.
On casino games, confidence is useless because it doesn’t have any bit of assurance to back your confidence.