Most people (who take prescription or recreational drugs) don’t go on a killing spree at the closest Westfield shopping centre.
Not everyone who does illegal things (like you mentioned) are drug addicted.
And it’s impossible for The System to function at a level where these unfortunate events can be avoided, always.
This incident is/should be a reminder that the world isn’t perfect and that we never know when some crappy/horrible thing may happen in front of us or too us.
