Who caused the financial crisis?...bankers, public etc ...both?

if you really want to know it was William Jefferson Clinton. He signed the "Community Re-Investment Act". This piece of law forced Fannie Mae and Freddie Mac to underwrite loans to people who had less than perfect credit. These loans then spun off into hybrid mortgages that were doomed from the start. See mortgages have always had a level of delinquency and foreclosure from the dawn of the first loan. That level was .004%.Now Freddie and Fannie had strict guidelines that were now very lax. We also had a very good sub-prime market that yes had higher rates for less deserving borrowers that functioned quite well up until this time. Every loan was eventually sold on Wall Street in an investment that earned investors and yes big companies like AIG good low risk returns in a predictable market knowing the over all foreclosure rate was historically very low.
Now comes the biggest hybrid mortgage scheme of all. It was called a pick a payment plan. This allowed home owners the option of paying 4 ways on their homes. Negative amortization (not keeping up with even the interest) - interest only (just paying the interest monthly) 30 year and a 15 year schedule.
These loans had a small introductory interest rate of about 2% and then in just a few month adjusted up to about 5%. This allowed borrowers to buy more house than they could ever afford other wise. So when the payments adjusted the vast majority of these people paid the least as it was cheaper than rent.
People are creatures of habit. They kept paying the least amount due and every month owed more and more on the note since they were going backwards.
These notes adjusted every 5 years for the first 10 years but on the 10th anniversary the borrower had then just 2 options a 20 year note or a 15 year mote. So if for instance a borrower took out an original loan of say $200,000 and paid negative for those first 10 years then they owed say $250,000 and the note recast. Yes now they had been accustomed to say a $1000 monthly payment that now jumped to say $1800 per month. This started the foreclosure rates to go up and up and up. This caused investors to pull their money from the sub-prime market first and one by one they lost funding and went bankrupt. Some 300 lenders from coast to coast. Then it started to hit the smaller banks as well then larger banks then the banks needed bail outs to stay afloat. Then AIG an insurance giant was invested in the housing market and they too needed to be bailed out as well because they were hit with huge losses.
Yes this all happened in the Bush White House but the old saying that a watched pot never boils did boil over in the Bush era it was Bill Clinton that put the pot onn the stove so to speak.
So when it comes down to it every one was to blame. The banks, the home owners, mortgage lenders, Fannie Mae, freddie Mac the investment world and yes Bill Clinton are all to blame. So look up the Community Re-Investment Act so you can be well prepared to answer the teacher with confidence not arrogance
I am a mortgage banker in TN

I put this squarely on Wall Street. Wall Street needed more mortgages to supply their mortgage back securities to investors. This lead to companies like Country Wide giving "creative" mortgages to people who couldn't afford a home. The banks would play on their dreams of "home ownership" to get them to sign into deals they would have no way of getting out. These people didn't know better and thought it was all legitimate. When the country slipped into a recession and these over burdened families started losing jobs, the house of cards came crumbling down. And the rest is history. Although the entire crisis stemmed from greed, it was Wall Street that got the ball rolling mostly through Fannie Mae and Freddie Mac.

Bankers (and averyone else in the investment business) first, then Banks, then fund managers, then Joe public. Politicians somewhere in there as well.
It amazes me when people (politicians etc.) say they, and everyone else, couldn't have seen the crash coming. What are they talking about? Turn this question around. What did you think, the party would go on forever, the growth going up & up? They MUST have known it was going to crash sometime, they just didn't know EXACTLY when (and exactly how) and were too greedy to jump off!

There is no one group of people who are responsible, but there is one WORD...GREED. The public got greedy in buying homes they could not afford based on uneducated assumptions such as "real estate prices always go up". Banks were more than happy to fuel that greed by their own greed. They offered exotic (notice that the you can spell the word TOXIC from the letters of exotic) mortgages to allow these people to buy homes they had no business being in. No one forced the other. They are BOTH to blame for the mess. Neither one of these groups deserve one penny of bailout funds as they have ruined the country and the real estate market for responsible people.

Well the obvious answer is the teacher caused the crisis. If you're in detention, you always blame the teacher. Not the bankers, not the public, THE TEACHER. Your teacher masterminded the crisis.