And why they still need crises to continue to survive: It’s due to the fractional reserve system, which allows banks to lend more money than they have. It incentivises them to go just a little beyond what is prudent. If enough of them do (as is inevitable), the system will collapse – UNLESS the the bad loans and unredeemable securities are dumped onto someone else. That someone was the banks governments and thus, ultimately, the tax payers.
Why didn’t the governments refuse to accept this white elephant? Because they were in the midst of a crisis where they desperately needed the banks. What a convenient coincidence for the banks. Interestingly, it happens during every major crisis.
22-minute video here. (Sources in the first, pinned comment underneath the video.)