The popular advice is we just need more confidence, more assurance, more chutzpah. But the issue with confidence is how we try to achieve it. Too often we try to win high self-regard in cheap ways. We undermine others, or we compare our achievements to those of the weakest around us. We conform to cultural norms, believing that what society values is what we value and that how society defines success is how we must define success. These cheap self-confidence tricks are unsustainable and can lead to narcissism during good times and depression during hard times.
In every aspect of our lives, there are many, equally valid ways to reach a positive outcome. There are always many ways to achieve a goal, gain expertise, or find success.