The foundation of the financial crisis was government policies that obliged banks to lower lending standards for “affirmative action” reasons, but the superstructure built on that foundation of sand was built by the banksters: some found that they seemed to be doing well with the lowered standards and lowered standards across the board, some realized the risk, bundled the risky loans into mortgage-backed securities and sold them to get the risk off their balance sheets (perfectly sensible given their fiduciary responsibility to their shareholders and depositors), some did both. The real problems came from the fact the banksters (and this is the reason the contemptuous name is merited) managed to pass the risky MBSs off as AAA-rated, rather than a more realistic just-above-junk rating and reaped personal gains in the collapse by fleecing investors by shorting what they knew to be bad investments but were hawking as gilt-edged.
There is plenty of blame to go around and neither government policy nor the top management at a great many banks and investment-houses should be let off the hook.
In many markets, there will be certain portions which can be very sensitive to government interference which changes various risky actions from having a slight negative expectation to having a slight positive expectation. If risky and unwise actions are sufficiently subsidized that they will turn a net profit for the people taking them, the extent to which people engage in such actions may increase by many orders of magnitude versus what it would otherwise be. This is entirely predictable, and should surprise nobody.
Unfortunately, once such behavior "takes off", it may be impossible for people to participate in the "real" market without joining in, since prices in the real market can be totally thrown out of whack by the government-assisted speculators. Those who simply want to buy a home they can live in are stuck competing with those buying homes they can flip.