They've managed to get the government to subsidize them heavily, price their competitor, cane sugar, out of the market, and support corn-based ethanol production. Of course, HFCS is worse for you and doesn't taste as good, corn in general isn't a particularly healthy staple food, and it makes no technical sense to make ethanol fuel out of corn in the first place.

The point is, policy isn't corrupted by billionaires, it's corrupted by large, politically powerful blocs, which may or may not have individual rich people in charge. It helps if the blocs are geographically concentrated, because the political system works state-by-state.