There are effective and ineffective way to use your money for power, of course. But many US politicians work for their wealthy donors. Most Senators are millionaires, no presidential candidates are poor.

The fact that some rich people only get part of what they want because they're opposed by other rich people, does not mean that their money didn't get them power. The Koch brothers got a lot of what they wanted.

And even if poor people, if there are enough of them and they are sufficiently organised, are able to oppose rich people, that still doesn't mean that the rich people don't have more power individually. Their resources make it much easier to organise, to buy influence and support, to reward politicians who legislate the way they want.

In the US, even more than in other countries, money is absolutely power.