A lack of self-confidence can come from such a variety of different origins that it's almost impossible to track down.
Gaining self-confidence doesn't have a one size fits all solution.
Although people sometimes experience traumatic events that result in a catastrophic loss of self-confidence, often it's more a case of a continual buildup of experiences that erode a person's confidence. Even in the case of a traumatic event, the event is usually just the final straw.
