The members of a collective hysteria are not hysterical, or crazy, or mad, or….
In the context of collective hysteria, if I say “people were hysterical” it does not mean they were *individually* hysterical in the running-around-like-a-mad-person sense.
Collective hysteria is a madness at the *collective* level. Individually they’re not at all crazy.
Not hysterical, but they are constrained