Banks make money primarily from interest on loans. They have a financial incentive to encourage the rest of society to borrow ever increasing amounts. That extra credit will flow around the economy and convince us that we're doing better than we were last year.
In an asset bubble, where the exact same asset is being exchanged for larger and larger amounts. Where each successive buyer has to borrow more and more money from a bank in order to win the auction. Who is the ultimately responsible for pushing up the price? The buyer? The seller? Or the bank manager greedily thinking of all the extra interest he will get?
Increasing credit so that people can speculate on asset prices is exactly what caused the financial crisis. We as a society had become dependant on that continuous increase in credit to keep our illusion of wealth alive. So when the inevitable finally happened and bank managers ran out or greater fools willing to borrow more, the economy collapsed.
There may be some need for banks to fund entrepreneurs, but they haven't been doing that at all. No, the current banking sector is a parasite, that has gradually convinced us to give them all of our disposable income. They don't make anything, they survive by sucking money from the productive sectors of society. They have taken the place of feudal Lords, gradually convincing the rest of us to pay them rent just so we can have a roof over our heads.