For the Koch brothers, electing the right candidate can mean a financial windfall. Republican candidates the Koch brothers back tend to favor fewer regulations on businesses and more fracking and right-to-work laws, to name a few. All of those issues benefit, to different extents, the bottom lines of the companies or stock prices or hedge funds associated with the mega-donors from whom the Koch brothers solicit big checks.
Social issues? Not so much. Organizations that spend the Koch brothers’ money may align themselves with conservative hardliners on abortion or gay marriage, but the brothers themselves — and most of their donors — are less concerned with social conservatism than they are with fiscal and regulatory policy. To them, political giving is an investment.
On the Democratic side, the opposite is the case. Heavyweights in the Democratic donor community pay the same tax rates as their Republican counterparts, and cuts to the capital gains tax or the higher brackets of the income tax benefit them financially, too. If fiscal issues were the only things driving their giving habits, Democratic donors would support the same politicians that Republican donors do.