While I've long thought that there was no way that housing prices could continue to appreciate based on the very simple fact that not enough people in this country make enough money to afford those prices, I certainly didn't have perfect foresight about everything. I didn't know that lending standards had gotten so bad. I didn't know that financial institutions were making such leveraged bets on big shitpile.
The other thing I didn't know was the magnitude of HELOC abuse, by both borrowers and lenders. Truly amazing.