Why would they do anything else? I imagine the pay and perks are great.
Besides, after a career in Congress reading bills that were written by lobbyists, a lot of the new lobbyists are probably looking forward to get a chance to actually write some bills.
Maybe what really needs to be done is that the politicians need to be told that we don't need any more laws (except for the law that says no more laws.)
Then they'll have nothing to do and therefore no incentive to be elected.