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.
It is not really complicated to buy large oil company stocks at $30 oil, because they pay dividends way better than bank CD’s, and as everyone knows fracking can not survive $30 /barrel oil. So we get paid to wait the turn around in oil prices. Opportunities like this do not come often, but in this case it was so obvious, it is crazy that more people did not jump on it.