Same thing that woke each and every one of us. Trauma. Not hard how to imagine how to propagate such a near universal trauma scenario. Evil and deception is embedded into every pillar of civilization, pull the thread from the biggest pillar, such as the puppet leader of the free world; all crimes that put him there, kept him there, and earned his placement, and the fallout will knock down all the other dominoes.

The question is how many will pop vs how many can deal. That's probably the % lost forever talk, not because they cannot wake up, doubt that is really a thing, but instead because they are so unequipped to handle the trauma of waking up. The more unprepared, the more rapid the awakening when it is forced, the greater the trauma of waking up, the more likely they pop.