The bunkers certainly help them survive a bioweapon pandemic, but then what would be next? Would they have the means to rebuild all of the supply chains in an almost completely automated way? Would they have the means to create new humans in such a way that leaves enough genetic diversity to survive other diseases that will stay in the world?
Of course they could have access to all the technology left over from before the said pandemic, but it doesn't mean much if there aren't enough people/machines to utilize them and keep them fixed. They would have to go without a lot of things like convenient private jet travel and complex manufacturing. This is not even mentioning when the food/medicine inevitably runs out.
This isn't to argue against you, just me wondering if they would take those kinds of risks. IMO they are probably too comfortable with what they have to rebuild everything rather than just capturing current governments and creating corporate dictatorships. If they screw up the former badly enough, we will be extinct after all.