It's interesting how different people react differently with respect to wealth. My relatively modest personal success is by no means solely a product of hard work - yes, I put myself in a position where I could get lucky, but I still needed a hell of a lot of luck. I didn't always know what I was doing, and things could've just as easily gone south.
That said, I've never felt the slightest bit of guilt over anything related to money. The way I see it, undeservedly, disproportionately good things happen all the time in our society, and they have to happen to somebody. Why shouldn't that somebody be me?