Three words: campaign finance laws.
When you let incumbents write the rules (remembering that all they really care about is re-election), you should expect that only incumbents will benefit from them.
There is not one single Senator worth the powder it would take to blow him or her to hell. They are a bunch of pompous gas bags who sit around and talk. They don't make anything, do anything constructive, or create any jobs . They are talkers not doers. They are so arrogant and self important that every four years a handful of them run for President. They don't run anything; don't manage anything; are not executives in anyway, yet they think they can run this country. The only thing they are actually good at is getting re-elected. I for one am sick of the entire bunch.