I think the Ayn Rand viewpoint--that self-interest is intrinsically a moral good and that capitalism is justified by this moral good--is not very widely held as a justification for capitalism.
I think modern American political discourse makes this a harder position to take. Which is not to say it's correct, because it's transparently not, but selfishness-as-Godliness is a firm part of the American right wing, self-styled libertarians included.
Greed's been good since the eighties, didn't you get the memo? =(
Greed's been good since the eighties, didn't you get the memo? =(