There's another interesting factor at play, which is that there can be unintended effects from wealthy people spending lots of money on politics, because you can't just directly buy votes.
For example, if Bill Gates decided to put $5 billion behind electing his candidate of choice in the next Presidential election, it would probably backfire spectacularly. Just looking at the numbers, he ought to be able to determine the election on his lonesome, since money talks and he'll outspend the other guy by a hefty margin. But the idea that a rich guy is effectively trying to buy the election would mobilize people to fight against it on a huge scale. You can see this at work in a smaller scale with the infamous Koch brothers, and the smaller scale backlash their spending has generated from people who oppose their views.
So not only do you have to look at how much people can and do spend, but also how effective that spending is. The marginal utility of political spending probably has a weird curve, and almost certainly can become negative once you reach a certain level.
For example, if Bill Gates decided to put $5 billion behind electing his candidate of choice in the next Presidential election, it would probably backfire spectacularly. Just looking at the numbers, he ought to be able to determine the election on his lonesome, since money talks and he'll outspend the other guy by a hefty margin. But the idea that a rich guy is effectively trying to buy the election would mobilize people to fight against it on a huge scale. You can see this at work in a smaller scale with the infamous Koch brothers, and the smaller scale backlash their spending has generated from people who oppose their views.
So not only do you have to look at how much people can and do spend, but also how effective that spending is. The marginal utility of political spending probably has a weird curve, and almost certainly can become negative once you reach a certain level.