Money is a problem in politics, but it's wrong to focus solely on money in federal election campaigns. It isn't that I don't think big money in campaigns is a problem, it's that I increasingly don't think it's the big problem, or certainly not the only problem, at least at the federal level. And as I actually had to tangle with the FEC back in the "MUST REGULATE THE BLOGGERS" era, I got a pretty good appreciation for the extreme genuine free speech issues in trying to regulate political advocacy. Political speech should be our most protected speech, and there is no regulatory framework that is going to be able to resolve the tension between speech and money very well.
Congressional staffers are looking to make nice with lobbyists to get higher paying jobs (and lower level congressional staffers really do get paid shit). People who work in regulatory agencies are looking to cash out with jobs in the industries they regulate. And, yes, former Cabinet secretaries are able to score the truly big post-Cabinet bucks.