Today it's bad mortgages, tomorrow it will be something else. Blaming the little guy doesn't fix the problem.
The US problem was they borrow too much money from the federal reserve. The federal reserve prints money against the debt by a huge factor of 7+ times. So every trillion borrowed from the fed creates 7 trillion in new US$.
It's all a sort of pyramid game, as long as they didn't get too greedy they could borrow forever, the US cash would increase by 7x the debt, if that went into American pockets then they could pay 1/7th as taxes and repay the debt immediately leaving them with the rest of the free money! Hoorah! Free money for every American! From thin air no less.
Except it's something of a con, and it only works as long as the US economy is growing so that people don't lose faith in the US$. Bush & Cheney got greedy, made too much debt, that created 'wealth' that got funnelled into home loans.
The loans popped. But then the valuation of those homes was way above their true worth anyway and lots of the new wealth went abroad to pay for oil, so the usual feedback loop didn't work.
So today it's the housing loans crisis, tomorrow it will be something else. They have no alternate source of funding but debt, and no other place in the world that will take their debt.
If you want to understand whose to blame, he's called Cheney and decided that debt didn't matter when it comes to getting elected, hence it doesn't matter full stop.
How was you rebate checks? Ever wonder how UGGov refunds you money it doesn't have? Notice the value of your saving in terms of real world goods has decreased? That's where your refund check came from, the devaluation of your dollar assets.