I wouldn't get too analytical about it. Usually it boils down to greed and power for
some . . . like Donald Trump.
A lot of it philanthropy for tax write-offs.
And then there's those who operate in the world of reciprocity ~ you scratch my back and I'll scratch yours. They support a particular party or candidate because they expect something in return. Those are the people who have congress peeing their pants and why we seem to get such strange legislation that seems to do more harm than good ~ like deregulating things that are there to protect us. Like clean air and water, for example. Or consumer finance protection. Or offshore drilling. To name a couple.
The rest of us are just the little people who vote. Promises are made to get our vote and forgotten until they need our vote again. We're the suckers who never learn. You know that, don't you?