they are corrupted by the very same corporations though

I mean, if you make decisions that affect the corporations profits directly, give a benefit to one company over another and then increase your holdings in one company or another before the benefits are announced to everyone else... you're a person who runs the corporation, and never has to be on the board. You make profits from the shift in the stock market, and you can even go long if you think you'll have even more positive changes to make for that corporations benefit.

If you're confused ask Nanci and Paul Pelosi, they've the epitomal example.

Lobbying

A lot of them are appointed former execs of the corporations they're supposed to regulate, and in America corporations are people so they can donate to PAC's and whatnot all in the light of day to influence policy making. There's no telling what happens when the lights are off. Thus, they are employed by these corporations gracious donations while at the same time placed in a position to make policy in government. Tail meet dog.

You think they're campaigning off of grandma's $5 donation?