Mass shooters are metally deficient, but are sane enough to plot and plan events where they can count on the least resistance.
Imagine that, crazies aren’t stupid enough to try to shoot up a place that may have armed victims!
Just because they are nuts doesn’t mean that they are morons; quite often they have a high IQ. Generally they know they will die, but want to have some fun and be “important” for at least a little while.
Wait a minute!
Are you telling me that they wouldn’t want a place were people can shoot back? /sarc.