We've spent blood and treasure around the world in Iraq, Afghanistan, Libya, Somalia, Syria, etc. over the last 20+ years and there are no doubt more terrorists who want to kill us now than before.
We can't bubble wrap society. Do TSA agents groping grandma and having everyone take off their shoes make anyone feel safer?
Also, let's keep in mind that people have always died for senseless reasons. This event is no more tragic than fentanyl overdoses or random violence in Chicago every weekend.