Why is it that some of the most creative people are the often most self-destructive? Is creativity fired by pain, or vice versa?

A friend of mine is a talented artisan; he creates amazing stuff from natural materials, things that transcend craft and become art. But he's drinking himself into oblivion. He has kids, he has obligations and commitments he clearly isn't really interested in being bound to. He seems to care, seems to want to be connected, but then he goes out until one in the morning and gets plastered, wasted, senseless. How he manages to get home intact is a mystery.

He's destroying his relationship with his significant other, the mother of his children. Having kids together is easy; making a family is hard. There's more here than alcohol; he seems to push himself to the edge of anything, be it his work or his personal affairs.

Is this part of our being? By being in balance, must we be therefore be moored in mediocrity? Do we have to destroy some part of ourselves or our lives in order to create? Is genius really just insanity lurking behind the curtain?