Attempting to fight them doesn't work as you've rightly pointed out. It just sets the stage for the next generation and wastes millions of dollars. Terrorists win. Obviously, what terrorists want is for people to be afraid. They want people to live in fear and they want to erode the freedoms and liberties we take for granted. Government crackdowns, surveillance etc will only erode our civil rights. Terrorists win. So, we carry on as normal as possible while using appropriate means to attempt to prevent terrorism that don't impinge on our civil rights. And, most importantly, we try and reform the ways in which the media covers these events. Yes, we want to know what is going on but the rampant sensationalism give terrorists their platform and helps disseminate the fear they are trying to spread. And just remember, you'll never stop someone deciding one day to jump in a car and mow people down, or grab a kitchen knife and go on a rampage, regardless of their motivation. But what resorting to these 'low tech' methods does suggest is that the techniques used to prevent mass casualty events could be having an effect.