Boycotts are one way to deal with out-of-control oligarchs, as are lawsuits, criminal investigations by honorable officials, and public education about their influence in politics. But there is one option that has never, to my knowledge, been exercised - one that might have the potential to succeed where other efforts have not: A business focused solely and entirely on the destruction of the Koch empire, pursued through intimate expertise in the personal psychology of the Kochs and their associates. Basically, run like an FBI anti-Mafia squad, but it profits from victories and the profits are directed back into fighting the Kochs' political efforts.
For legal purposes, the business couldn't be publicly-traded so that the people running it would have no obligation to seek all possible profit: The only permissible profits would be those currently residing in Koch business, so it would be developed on an evolutionary basis to target only one set of competitors/revenue sources. In a way, what would occur is that there would be an "Anti-Koch" conglomerate that mirrors the Koch portfolio while draining it of resources, interfering in its political and business activities, and directing the acquired resources toward opposite objectives.
There needs to be a psychological shift in how we deal with people like this, because they are no longer just arrogant rich individuals, but somewhat nation-states unto themselves with their own institutions behind them. We need to fight them like we fought the Cold War - cut them off, isolate them, deter them from further expansion, and drain their power. And really the Kochs are just the most prominent examples.
Generally speaking, it's worth exploring the concept of "Anti-corporations" that exist to mirror, thwart, and drain the resources of abusive business institutions and their backers. They would be business institutions in their own right, but they would be structured such that the only way they could make money is by attacking the revenue streams of one particular corporation or set of corporations. They would be hyper-predatory and focused, like a kind of Terminator corporation. They could be designed to end once the other corporation has ended or been acquired by its own mirror, with a lot of compensation for (Democratic, obviously) executives so that there's no incentive to keep the game running beyond its natural endpoint.
What do you think of the concept of Terminator corporations? Big Business in America already operates as Terminator corporations to the US Constitution, so maybe we need to up the ante and build some predators to go after them to protect this country. Competition among themselves obviously isn't doing the trick, because they reach an equilibrium where they're basically cooperating with each other to tear down this country. There need to be institutions - hungry, predatory, for-profit institutions - whose sole purpose is to attack these businesses, and that cannot branch out to any other prey.
8:46 AM PT: How about "Adopt-a-Nemesis"? Through a nonprofit, individuals sign up to track and figure out ways to fuck with one particular corporation for some period of time, and people who sign up to fuck with that company compete with each other for achievements and (fully legal) lulz.