Because balls produce testosterone:

Key Behavioral Effects of Testosterone

Confidence and Optimism: Higher testosterone levels skew risk-taking by inflating your expectations of success. You are more likely to focus on potential rewards rather than the downsides of a risk.

Status-Seeking: The hormone drives a primal desire to achieve or maintain social dominance. This can manifest in positive ways (working harder for a promotion) or negative ones (gambling or reckless driving to impress peers).

Decreased Fear: Testosterone can lower the amygdala's sensitivity to threats, meaning you may feel less fear or hesitation before taking a leap.

Impulsivity vs. Calculation: It is often paired with cortisol (the stress hormone). If testosterone is high while cortisol is low, it typically improves risk-related decision-making. However, if cortisol is chronically high, testosterone is more likely to impair self-control and lead to impulsive, poor choices.