Several times in the last three years a large percentage of the "money" in the stock market has disappeared pretty much overnight. When I say "money" I mean that definition of money that comes from the 2000 year old adage: "Everything is worth what it's purchaser will pay for it." Publilius Syrus, first century BC. Every cent (every one of which is a number written on a piece of paper or some 001110001011's stored in a computer file) invested in the stock market is that kind of money. It has no intrinsic value of it's own; it's only as valuable as you can convince someone it is... IF and when they buy it. The money that the brokers "earn" comes from moving these numbers around and keeping a little (or sometimes a lot) of the numbers for themselves (then they sell it, quick). The numbers go up and down, up and down.
A bubble pops, some mega crook gets exposed, the 100 year old Emperor of Japan dies of natural causes, a mega speculator gets out of the market suddenly; there can be many causes. Recently, we had the idiots in the Tea Party trying to get the U.S. Government to default on it's debt... But I've always said that if someone on the floor of the NYSE just yelled, "The president's been shot!" loudly enough, you could watch the big board spiral down. Is this a great system or what?
A few years ago I got lucky. I bought something with real money a week before the 2008 crash. I might have bought some stock with that money but instead I bought solar panels for my roof. Guess what? They're still up there, 100% as good as they were the day I bought them. The market lost 40% of it's "value" over the next few weeks.
Take your money out of the market now and buy something durable that the bastards can't turn into a valueless piece of paper tomorrow. If everyone with $25K in the market bought an American car tomorrow, the economy would boom and half of the overpaid, under regulated, and under taxed money moving stock brokers would have to get a real job. Maybe even making cars.