Adelson is contributing millions of dollars to the Romney campaign (after doing the same for the Gingrich campaign). As you’ve pointed out, the campaign is unlikely to change the outcome of the election. Even at millions of dollars, Adelson’s contribution is a drop in the bucket for Romney and unlikely to make much of a difference in the campaign. If Adelson wanted to impact the direction of the country, why not divide his contributions in five and give them to the five Senate races rated tossups? That would be a more effective use of it.

So why does Adelson give all this money to a presidential candidate? I can come up with four (non mutually exclusive) reasons.

1. He has something he really wants the next President to do and this buys him the access to ask for it.

2. He doesn’t understand the limited relevance of campaigns and the declining marginal utility of contributions.

3. He wants to displace the Koch brothers as the rich bogeyman of the left.

4. He has so much money that he doesn’t mind spending it in a way that has a very small probability of affecting the outcome of the election. (by the way if this is true, could there be a better argument for increasing marginal tax rates on the very wealthy?)