The issue was not so much about who the big banks loaned money to, but
about who invested in them. In this capacity, they were assumed to be
safe investments, but they were cooking the books. The crisis focused
on the mortgage industry, but was much broader than that. Essentially
they would buy up debt from smaller banks and mortgage brokers and
bundle it into derivatives of various kinds to sell to investors. They
depended on the long history of the average person working hard to get
out of debt. This had worked for Fannie Mae since the '30s and for
Freddie Mac since it was formed in the '70s and had provided liquidity
for mortgage loans. What JP Morgan discovered in the '90s was a set of
analytic tools that predicted risk in these types of investments and
this started a rush across the industry to develop ever more exotic
derivatives and investment schemes. This dominated the private
secondary mortgage market by the mid 2000 decade and was expanding into
other types of credit as well. To add insult to injury, the rating
agencies, essentially federally licensed companies that were supposed to
give investors a measure of the safety of the investments in these banks
were in competition for the business, paid for by the banks, and they
inflated their ratings. As a result, a lot of very conservative
investment funds like retirement funds, state treasuries, and other such
organizations were heavily invested in these banks on the false faith in
the honesty of the rating agencies. Even foreign countries were
investing heavily in the big banks.
The short answer to your question is that the implications of a failure
of these large banks would have had repercussions across the entire
spectrum of finance. The money that you put away for retirement would
have been gone. State governments would have failed. It was a very
serious situation, potentially even worse than the Great Depression.
There was really no choice but to bail them out, as distasteful as that
was. Unfortunately we have not done nearly enough to prevent another
crash. Bernie is correct in arguing that we need to break up the big
banks. Unfortunately I doubt that he will be able to do it. We have
allowed them to become too powerful.