Ive Heard EnoughI have wrote on this before but apparently it was lost in the mass panic.....
The veil is an enchantment. It acts as a lense to prevent humans from seeing and entering the magical world. It has nothing to do with demons. Demons have been able to come and go in this world for ce nturies.
The whole issue about the veil dropping is because if enchantments aren't maintained they will fail. If that happens humans will see what's REALLY in the world including malevolent beings that will eat them.
That's it. If you can't handle that then step aside, let the grown ups handle it and just try not to get in the way. Simple as that.