It's the kind of people they are. Low, petty, small and mean. So in order not to have to pay more taxes, in order to prevent anyone from making them contribute to a more just and fair society, they give hundreds of millions of dollars to failed right wing political hacks such as Karl Rove, who piss those hundreds of millions away, with nothing to show for it. They might as well be doing lots and lots of really really expensive drugs.
So, as a result of this year's elections, these big money Republican donors will have to keep paying taxes, hopefully they soon will have to pay even more taxes, and they also pissed away hundreds of millions of their own fortunes to no purpose at all. You'd think they'd want to save their money, next time. They might not have a choice about taxes, but they do have a choice about continuing to throw good money after bad. If they care so much about preserving every penny of their staggering wealth, perhaps they ought to consider not wasting it.