Well, terrorists are winning. But the goal of terrorists is not to make "everyone's life to be worse", it is to force political changes.

In the case of the Islamic terrorism, their goal is to spread the authority of Islam.

So, for example, since the Charlie Hebdo attack, nobody will publish any image of Mohammed. We are now all following that part of Islamic blasphemy law, because we're afraid of their enforcement squads. So in that spot they succeeded.