They literally don't, though. They're employees of the party. And the party is contracted by its mega-donors and future private sector lobbying clients.

Liberal democracy is an illusion of choice. You're shoved into a gerrymandered district, pumped full of hateful ideologically brain-poison such that you hate everyone outside your partisan unit, told to vote the party line or get blamed for an implosion in the standard of living, and then ignored until the next election cycle.

Then, every two years, we get a bunch of voters with Buyers Remorse after the incoming Congress implements a policy of payouts to the corporate sponsors. Occasionally, we'll see the winning party brutalize members of the losing party. But that's the only real "reward" for being on the winning team - watching the schlubs in the opposition get their faces shoved into the shit.