again this crap, the money needed to set up a mining operation that could overwhelm 51% of the network at this stage would be best used with that same equipment to secure the network instead, and earn the normal reward from the mining activity
would be more feasible for chinese to do this, because they are already at roi stage
You don't understand, the 51% attack is to destroy the infrastructure of bitcoin in order to save the established banking system in the U.S. and worldwide.
They will have to spend a ridiculous amount of taxpayer money. In democratic systems like the U.S. and other countries, those people who came up with that plan will be voted out of office very quickly since they would be spending the taxpayer money on something that has no return at all, attempting to destroy Bitcoin. There is no gain for the populace and those politicians will be replaced by people who are either neutral or pro-Bitcoin.
Even if the attack was to destroy the infrastructure, as soon as it stops, the network will rebound. Those that have faith in Bitcoin will find a solution. Probably something like a block or small code change that drops the difficulty back to a usable level by the rest of the miners. After a few months, Bitcoin will be back on track.