They are ment to listen to the people in their state and put forth bills or amendments to bills to help the people of their state they represents.

What really happens is they enrich themselves with insider trading and do stunts to keep their name in the headlines even if it hurts people they represent. The reason this works is journalism is effectively broken where it’s all about sensationalism vs actual truth. So they more crazy the stunt the more your name is out there.

They put forward amendments and bills that were written for them by corporations that donate to their campaigns / lobby=bribe.

The reason it works is the vast majority of people ether vote because their party affiliation is wrapped up their personal identity or vote for the name they last heard. Also the vast majority of people don’t vote at all. So they are not incentivized to actually represent.