Under the right stimulus, I think a perfectly sane/mind could do some pretty bad stuff.

Maybe it will be more targeted, but similar to road rage issues or people just being pissed at their situation or lot in life, a poor unconnected society leads to more of these blow ups.

I know of a divorced professional pretty ticked off at his situation who can decide to take it out.

Trying to correctly identify these things will be very hard and you will have tons of people probably locked up.

Sounds like that movie that locks people up before they commit the actual crime.