Why be a senator for a long time? In many ways it isn't a very good job. Of course it's a better job than, say, coal mining. But most of these people are wealthy enough, or could leave the Senate and become wealthy enough pretty easily, that it's a choice. Sure some want to do good and see that as a pretty good place to do it. I'm not so cynical that I think all senators are bad. As for the rest...well, we don't have an actual aristocracy in this country and yet some people think they should be members of one. The most ridiculous deliberative body in the world is the closest you get.