They've actually gotten a great ROI from their lobbying:

>Only the Kochs know precisely how much they have spent on politics. Public tax records show that between 1998 and 2008 the Charles G. Koch Charitable Foundation spent more than forty-eight million dollars. The Claude R. Lambe Charitable Foundation, which is controlled by Charles Koch and his wife, along with two company employees and an accountant, spent more than twenty-eight million. The David H. Koch Charitable Foundation spent more than a hundred and twenty million. Meanwhile, since 1998 Koch Industries has spent more than fifty million dollars on lobbying. Separately, the company’s political-action committee, KochPAC, has donated some eight million dollars to political campaigns, more than eighty per cent of it to Republicans. So far in 2010, Koch Industries leads all other energy companies in political contributions, as it has since 2006. In addition, during the past dozen years the Kochs and other family members have personally spent more than two million dollars on political contributions. In the second quarter of 2010, David Koch was the biggest individual contributor to the Republican Governors Association, with a million-dollar donation. Other gifts by the Kochs may be untraceable; federal tax law permits anonymous personal donations to politically active nonprofit groups.

https://www.newyorker.com/magazine/2010/08/30/covert-operations

So they'd spent about $250M in publicly traceable contributions by 2010. Let's double that for any contributions they've made since 2010, and multiply everything x 10 to make a guess at their untraceable contributions, so a ballpark of $5 billion total.

$5 billion is only about 4% of their $120B net worth. They've almost certainly saved that much from favorable taxes and delaying climate change legislation, so it's been a pretty good deal for them.

May they burn in hell.