There's 200 other people on the flight that think this plane is going to crash instead of thinking this plane is going to land safely and a ransom is going to occur.

Prior to 9/11 hijackings were rare but still occurred with everybody living [1]. There is a notable truncation in the list after 9/11 of incidents per decade (across the world; so nothing special about TSA).

https://en.wikipedia.org/wiki/List_of_aircraft_hijackings#19...

Locking the door of the cockpit, actual on the ground policing in terms of monitoring terror cells.

Better cooperation between intelligence and law enforcement agencies