Critical mass:
Is the smallest amount of fissile material needed for a sustained
nuclear chain reaction. ...
wikipedia.org/wiki/Critical_mass_(nuclear)
or:
Critical mass:
Is a sociodynamic term to describe the existence of sufficient
momentum in a social system such that the momentum becomes
self-sustaining and fuels further growth.
wikipedia.org/wiki/Critical_mass_(sociodynamics)
That is to say:
When crazy people outnumber normal people, craziness becomes the norm,
and normal people become the crazies.
Visit some of these websites; it's cheaper than going to a shrink.