On the Economy, and Barry Zito

I need someone to educate me here. I pray to whoever that I'm not about to sound like the biggest asshole on the planet--but this financial crisis we're in - shouldn't some of the blame go to the people who failed to pay back their loans? I mean, in brief and simple terms, a big reason for this awful economy is that banks gave out a ton of loans that didn't get paid back, and that is why they went to hell, right? Did these people not sign a contract promising to pay X amount of dollars back in Y amount of time? Don't get me wrong--the banks are responsible for their own fuck-ups. And these bad loans were fuck-ups. Huge ones, obviously. And they are the ones who are supposed to know what's up. It's like, even though I was happy when the Giants signed Barry Zito for $126 million and I thought it was the right move, it doesn't mean I'm not allowed to be mad at Brian Sabean for doing it now. He's the one getting paid to evaluate talent and build a team. Just like the banks should be able to evaluate whether someone is gonna be able to pay their bills. So they get most of the blame. But does Barry Zito not get a lot of the blame too? Should I not be mad at Barry Zito along with Brian Sabean? Do those that defaulted on loans deserve some of the blame for this shitty economy? This is my question to you. Feel free to educate me.
My guess is that the banks were all "oh dont worry. You'll be able to pay this loan. You're house will only get more valuable". That seems like a logical explaination, and also shifts pretty much all the blame to the banks. So maybe I don't need to get educated.
BTW, I say "banks" as an encompassing term for all of the "fat cats on wall street" that people love to bitch about.