This speculation of yours must be flawed.

"My guess is for them to buy some insurance or have bets that when the economy falls, they will make money (something called CDXI).

Basically, the banks know the financial system is screwed and they want to make money off of the downfall of the entire financial system." When I look up CDXI I find a pharmaceutical company.

I don't see how the banks can do this because everyone is on to this scheme so who would sell them insurance.

This might be ok advice for a young persons but a lot of people are already over 50! "I have faith that the market will eventually flourish under better regulations, hopefully before I reach 50." What advice would you give them?