I recall in one of the interviews he said he <inexact quote, summarized>

"I do appreciate money and it is needed to invest in ventures, but I personally I'm not in it for the money. I can already buy everything I could want."

EDIT: I am just supporting parent post's claim that

"but frankly I would respond by pointing out that Elon really doesn't seem to be in it for the money, but rather despite the money."