No shit. Why do people in this thread keep telling me that people are stupid like that's a news flash to me? The fact remains that it is stupid, and especially for educated people like the laywers/doctors/etc mentioned upthread, it's sufficiently obvious stupidity that there's no excuse. Yes, I know, that describes a lot of other stupidity. Much of our history as a species is inexcusable.

Edit: though I should be clear: people demonstrably do often learn to discount obviously unreliable sources. Not all the time, but pretty often in the easily verifiable cases, especially where they don't have a major emotional stake.