Sometimes it was drugs, sometimes it was just plain stupidity. Looking back with the benefit of hindsight.
Hindsight can be a wonderful thing.
But for every good career move in rock and pop there have been any number of bad career moves. Of course, just with all of us, the participants rarely knew they were making blunders at the time. But it's fascinating to look back, with hindsight, and mull over some of those big mistakes and think about what might have been. And maybe even something is learnt along the way. Dusty Springfield, and the Memphis albums that never were.