Being a politician. The base pay is not too great, but usually more than average. But, the big money is in getting bribes -- excuse me, political contributions.
BTW, another reason is that since medical care is so expensive, they get great medical benefits. Much better than what most people get under the present system, what most people will get under OBAMA'S proposed socialized system. Do you think YOUR congressman or senator is going to have to wait for months or years for THEIR surgeries or treatments, as do those in Canada or Britain?