I think it goes both ways. Tom Price, Ryan Zinke and Scott Pruitt are clearly in it for the monies, but people like DeVos are independently wealthy and she is very much a true believer. The book seems a bit quaint now, but John Dean’s Conservatives without Conscience described research being done on “Right Wing Authoritarianism” and listed three general categories. There are the general RWAs that make up the rank-and-file and there are the the Social Dominators who don’t actually believe in RWA, but they adopt whatever belief system they feel will benefit them the most (Trump, Price, Zinke and Pruitt all fit this descriptor in my mind) and finally there are the people that take on aspects of both (so-called Double-Highs).
DeVos and her brother feel like DHs to me. They fully buy-in to the RWA mind-set, while also maneuvering to position themselves most advantageously within the framework of RWA beliefs to cash in on it.