Pulling these kinds of attacks - especially undetected - requires a certain level of intellect and education that should also be unaffected by things like subst

Pulling these kinds of attacks - especially undetected - requires a certain level of intellect and education that should also be unaffected by things like substance abuse that hamper systematic planning. People with that level of capability almost always manage to create sufficiently comfortable life situations for themselves that they they lack motivation to do so. Problems happen when either (1) technology to do harm becomes commoditized and freely available so less capable people can acquire and use (eg. Easy conversion of semi automatic to automatics, commoditized hacks for script kiddies) or (2) capable people feel they're been sufficiently wronged that they don't care about the consequences of revenge (pretty much all the really big headline terrorist actions) Most intelligence activity on prevention focuses on (2) since pulling off such actions generally requires the capable planners to coordinate with less capable "feet on the ground" who can give things away. However capable people acting alone which happens occasionally is pretty much impossible to stop (Timothy McVeigh, Ted Kazynski, Kaloyev)