Because given the historical precedents, they know they will probably die peacefully in their beds before they have to pay any real consequences for their actions. Sure, a few dictators at the very end of their reign had to pay some consequences, but their cohorts? Soviet Russia, South America Banana republics, the aristocratic european families that enabled fascism and nazism...
Probably a few CEOs great grand-childs will probably have to write how they're very very sad that their long forgotten relatives have destroyed most of the planet, and how they're just so lucky to be among the few that are still living a luxurious life somewhere in the Solomon Islands.