Politics is a zero sum game in which you spend 500 billion dollars to no avail except for forcing your opponent to spend 510 to win. Millions if people are already trying to win this zero sum game already. Might as well ask "why not just win the World Series of poker, then use that money to fund Miri?"
I don't think this is true in most political contexts. Political activity is often positive-sum or negative-sum.
People do make compromises that improve total utility. Special interests demanding special handling aren't always wrong -- sometimes they do have special concerns that can be met cheaply, and that ought to be.
Conversely, political process can be negative sum. It sometimes results in inefficiencies -- either rent-seeking or awkward half-measures that produce less utility than if one faction had total control.
This is a thread where people can ask questions that they would ordinarily feel embarrassed for not knowing the answer to. The previous "stupid" questions thread went to over 800 comments in two and a half weeks, so I think it's time for a new one.