Those who participate in risky sports often do so to confront their fears. For example, rock climbers are more likely than others to have once suffered from a fear of heights. Those who participate in such risk-taking activities also have more self-confidence than others
it is probably true that confronting one' s fears increases one' s self-confidence.
In general, people who currently participate in risky sports had above-average self-confidence even before participating in any risky sport.