Why do people fall for hoaxes?

According to Terry Goodkind, the Wizards first Rule applies here. The Rule states that:

People are Stupid. They'll believe anything you tell them, either because they WANT it to be true, or they're AFRAID it's true.

With hoaxes, the first part of that rule comes into play.

Believe none of what you hear and only half of what you see or read.

It's not that people are stupid, but naive and too trusting. Having a defensive mind-set is learned through time and experiences-or from passed on experiences by others. The only stupid ones are those who do not learn from their previous mistakes of getting hoaxed or falling for a scam and falling for it again.

Also many times hoaxes/scams also prey on emotional responses and sometimes people act on them with a knee jerk reaction rather than taking a minute to think about it before passing it on or falling for it.

There is my two cents worth.

Hoax should never be entertained & measure should be there to give actual or correct information. Since hoax or false information only brings bad reputation.