There is no one real source of blame for the housing bubble and financial crisis. There were people who could have done something to stop it (Clinton and Bush administrations, Congress (either party at various points in time), Greenspan). There were regulatory agencies with no teeth that set policies in place that encouraged banks to make risky loans. There were homebuyers that stated more income than they made, and banks that didn’t bother checking those claims. There were some very smart math nerds at banks that made a very fatal error when averaging out risk, ignoring the possibility of systemic risk.
This is what makes it so frustrating for the average american. There’s no easy scapegoat. It’s easy to paint your own personal politics onto it. Republicans can blame Fannie, Freddie, the Democrats and poor people. Democrats can blame Bush, the Big Banks, Republicans, and individual greed. The truth is a lot of people screwed up.