I think John King on CNN got it right when he said there's a small 'piece of the pie' here who are those who can't deal with a black man being elected president.
I think the better explanation came from Rachel Maddow yesterday when she went through all the ways the birther conspiracy was a source of financial gain for various interests and individuals.
Sure there are small amounts of racists in every group but the majority of this stupid crap isn't about obama's race as so many are quick to claim. Its was an easy avenue of attack for those that don't like his policies and ideals....i still think it was an intellectually bankrupt way to attack obama, considering his record gives those who oppose him plenty of ammo, but even so those calling it out as racist are just as bad as the birthers.
And i'm sure trump will write a book on his "exploits and adventures in investigating obama" which fits right into what maddow said.
People who assume that birthers are racists should look in the mirror and ask "why do I automatically assume they are racist because obama is black, do I actually have a prejudice against non-black people?"