[chii]

> Societies also implemented security measures after terrorist attacks.

i would argue that those measures are costing more than the attacks themselves. It's security theater - high cost (in terms of time and resources), high visibility (politically). But doesn't really prevent any terrorist attacks, because terrorist attacks are fairly rare all things considered.

So you can say that those terrorists' attack succeeded in making the lives of those they attacked worse, and it's because we let them dictate due to "fear", rather than rationally ignore them.