I bought lot of oil related stocks when it was around $30, earlier this year. It was the most obvious and once in a decade opportunity to make easy money. Sold everything last week, in conformation with my discipline to never get greedy, and one can never go broke cashing in profits when it happens in a short time.
A buddy of mine did the same thing you are talking about when all the oil service stocks started crashing. He bought big. Said he would either make a pile or go broke, haven't seen him lately but I'm sure he didn't go broke.