Stupidity and Obstinacy, to which there are contributing members here at Free Republic. Here is a more extensive explanation.
So pretty much all the conservative bloggers, legal minds, commentators, think tanks and foundations are just stupid and obstinate?
Another possibility is that Birthers are simply wrong and never get anywhere for the same reason Truthers never get anywhere. Which is, because they’re wrong.
But it makes them happy to think that they are among the select few who have figured things out. There is that.