Inner demons most likely.
Whatever it takes to build world class companies out of nothing, luck and timing is only one small part. The rest is what makes people like Jobs unhappy, or perhaps discontent for most of their lives.
One assumes the demons inside Allen and Woz quietened down and stop driving them on.
This of course sounds great till you look at Bill Gates and ask does be look any more unhappy than me? No he looks a lot happier
Bang goes that theory