You must be disconnected from reality to imply that people's fear is somehow irrational and unjustified.  Of course it is a suicide bombers goal to kill as many innocent people as possible with their homicidal bombs.  Of course it is to instill fear.   The State Department issued a travel warning to all Americans about traveling to European  destinations.  They didn't issue that warning to instill irrational fear.  It is in response to reality.  If people are experiencing fear it is not because they are paranoid or irrational,  it is because they are perceptive and aware that ISIS and other non State actors have declared War on them.