Why do Republicans insist that tax cuts, for the wealthy, are the only way?

I suspect its because most Republicans are selfish and delusional...They have to be since their "God of Trickle-Down Economics," Alan Greenspan HIMSELF told Congress last year that this theory was flawed and that it failed; yet, none of the Republicans seem to want to admit that even when he facts are staring them straight in the face. Sick and sad, I say...