It's just a numbers game. We are not perfect, and nothing in the physical realm is perfect, even on electronic chips bits can be flipped by cosmic rays and lead

It's just a numbers game. We are not perfect, and nothing in the physical realm is perfect, even on electronic chips bits can be flipped by cosmic rays and lead to errors. With every action or decision we take there's a non-zero probability it is a mistake. Over the course of our life we make a ton of decisions. The only thing you can do is reduce the error rate.