Dumb answer: because SS and Medicare pay for "real" goods and services and have to interact with the main street economy, whereas FDIC acts in conjunction with the Federal Reserve, and the effects aren't seen by the public - the money isn't "spent" on something, it's just not _not_ there.

Also, the original statement is not quite correct - FDIC is funded by a special levy on all US banks, so while on principle it's backed by the "full faith and credit" of the US government, in actuality the money comes from the banking system itself.

Edit to add: from the article:

>The FDIC is funded by its member institutions through premiums and assessments paid on deposits. And, if ever needed, the FDIC can draw on a line of credit with the U.S. Treasury.

So, if you're a bank, you have to be a member of FDIC, or the banking regulators come and take your bank away. Being an FDIC member means you have to give them money, pretty much according to their whim (or they come and take your bank away). If that's ever not enough to fund a "not bailout", FDIC can get a loan from the Treasury, to be paid back from those premiums and levies on the banks over a period of time.

My personal theory: if people even had the remotest inkling that the insurance would fail, then it is next to useless. The point of it is to prevent the majority of people from inciting a bank run since they know for sure that their money is safe. It's a bit of weird game theory.

There is no equivalent to a bank run risk on SS/Medicare so why put it in. Putting it in also means that these programs could cause massive inflation if the US Gov had to print money to finance them.

Because no one has promised that SS and medicare benefits will stay the same forever.