These families mainly derived their wealth from just three industries: finance, energy, and real estate. These aren't sectors where innovators bring new services and technologies to the people, but rather where capital owners use their market power to squeeze the hard-working public. Wall Street hedge fund and fossil fuels-related donors, like the Kochs, have donated a staggering amount of money to mostly Republican candidates. Democratic-leaning billionaires exist, they simply do not come anywhere near parity in terms of giving, meaning that Republicans' boogeyman image of George Soros is a complete myth. The Republican primary is currently more competitive than the Democratic race and that disparity skewsthe New York Times' numbers to the right as Republican donors have more reason to give money earlier, but the ultra-rich still leaned massively towards Republicans in 2012.
Consequently, the candidates that the ultra-wealthy favor now agitate for low or even no taxes on finance, reduced social services, and corporate welfare spending for their very benefactors. Billionaire oligarchs purchase puppets on a string who kowtow to their particular demands, while politicians, who themselves are also rich, instead ignore the everyday citizen.
This is what the death of American democracy looks like. It's time to acknowledge that we no longer have a democracy, but a plutocracy: Government of the rich, by the rich, for the rich, brought to you by Citizens United and the Supreme Court.