Our country (and the world) is run by rich people, it always has been. And that isn't necessarily terrible, our country has done pretty well for itself. I think the combination of capitalism and personal liberty have played massive roles in our overall success over the last few centuries.
But unfettered capitalism doesn't work. You get the robber barons of the late 19th century; a few people with all of the money and capital, and everyone else just begging at their stoop. Or unregulated bubbles that lead to collapse of our economic systems, like 1929 or 2008.
Capitalism is kept in check by a government beholden to its voters, a free press, and collective action of the masses (e.g. organized labor). Finding the right balance is the trick because an overly restrictive government can stimy growth, but unfettered capitalism allows those with power to aggregate more power, leading to eventual uprising and social collapse.
So, as shitty as our government is, and as much as government is also controlled by those same rich people, it still stands as one of our few protections against straight-up oligarchy. We could have better protection if we can try to minimize the effect of money on elections, and if we fix the information ecosystem to make it harder for people to be propagandized. These are both enormous problems without an obvious fix in sight, so your cynicism is warranted. But I think we will figure this stuff out, eventually.