just purely as a thought experiment and devil's advocacy: to create new avenues of growth and control for the oligarchy. The fall of the Soviet Union, for example, turned out to be a boon for them and they were able to replace the politburo with their own fiefdoms. By destroying the US goverment functions they will be able to privatize the profits (for their companies) and socialize the costs (pollution and shitty water) for the rest of the population. The price of clean water will go up and the people that can afford it will buy whatever anti-PFAS tech they're selling (providing growth for their companies), and the poor well...who cares. They will obtain greater leverage with the US government because they will be seen as saviors since the government will have no competent agencies left, including the military. And the government will helplessly cede more and more power over to them.