That power has been given because there was trust that the US would not fuck you over. That agreement seems to have been canceled by the US, therefore that power can be removed, too.

The EU didn’t give power to the US. The US took it after the European states got decimated after WWII. Power is not given, it’s taken.

Of course power is given. If enough people decide to ditch YC and HN tomorrow because the CEO said something stupid, it will sink into meaninglessness.

Obviously that depends on the amoount of people and how far something has to fall, but it can happen. Other things will fill the void. Same goes for nations if you look at former superpowers like France, Spain or the UK. Everything can break.