TBT:
“But why would anyone choose to become a destructive monster?”
Because people have free-will, and can do whatever they please. Have you never done something just to spite, or even hurt somebody? I certainly have, and I believe we all have that monster within us. We can choose to fight it, or we can choose to strengthen it.
“Besides, wicked people are full of regrets (chazal). Not being content and always regretting, yet repeating the same exact deal in the same again and again, is certainly the makeup of an unhappy etc person.”
Certainly, being wicked will result in a regret-filled, unhappy life. But that doesn’t mean somebody starting down the path of wickedness has physiological problems. They are just normal people who have chosen to follow and strengthen their inner monster. Only later does the path that they have chosen ruin their lives.