Re. Tylenol, 7 people died in an isolated area, and the response was national legislation and money and materials spent tamper-proofing every drug made since then. People are still scared of Halloween candy being tampered with (which in and of itself has never been recorded as happening). By that logic, we should have outlawed cars years ago; more than 7 people die every day in accidents.
Re. military action, the occupation of Iraq had little to do with stopping "terrorists." If you recall, we invaded because of our fears of WMD's--which of course, turned out not to exist. You would also do well to recall that we have had terrorist attacks since we invaded: remember the shoe bomber, or the underwear bomber, who both successfully smuggled explosives into a plane after military action had begun? Only their own incompetence and the alertness of the passengers prevented tragedy--the military had nothing to do with it. To suggest otherwise is, frankly, simple ignorance.
Finally, I'm reminded of a Simpsons quote: For $100, I can sell you a rock that prevents tiger attacks. It really works: I've never been attacked by a tiger since I bought my own rock!