Devil's advocacy:

The Republican party gives a shit about the average American because it's easier to earn votes than to steal them. As the majority of Republican financial tenets are detrimental to the rank-and-file proletariat voter, it becomes necessary to create a social platform that represents the needs of that rank-and-file so that they become willing to vote against their financial interests. Thus, "trickle-down economics" gets a bye in exchange for "prayer in schools." The "death tax" gets rescinded in exchange for the Defense of Marriage Act. Marginal tax rates decrease while restrictions on abortion increase.

The people economically disadvantaged but morally advantaged by Republican policies don't have a lot left over for political donations. As such, you can view the Koch brothers as benefactors of the proletariat - giving of their hard-earned cash to advance the social policies deeply desired by a proletariat that doesn't have the means to mount a defense against those tax'n'spend liberals and their union immorality.

Okay, gotta go wash my hands now. That felt icky. Just pointing out that it doesn't take extreme mental gymnastics to wrap your head around giant, shadowy superPACs.