You really can have too much of a good thing! Too much of a virtue becomes a vice.

• Fearless dominance, for example, may contribute to skillful leadership in the face of a crisis, or to reckless criminality and violence
• The seven deadly sins might very well have started out as ambition, relaxation, awareness of one's good work, righteous anger, a healthy sexuality, and enjoying a good meal. It's all a matter of degree.
• Aristotle argues that virtue is achieved by maintaining the "Mean", which is the balance between two excesses.

Related:

• Too much choice can cause unhappiness, bad medical outcomes, and misinformation
• Goldilocks principle