I really can't seem to emphasize this enough: that which you volunteer (for some token reward) will eventually be taken for granted, expected, and required.
People seem to think that additional security measures are always temporary, assuming blindly that some day we'll declare the terrorist threat gone and lower our guard, easing restrictions. Our security/safety measures are built on the fear of terribly unlikely events: we can never be absolutely sure the threat is gone, and the threat carries a quasi-infinite cost. (Are you willing to put a price, a value on someone's life?) Infinitely unlikely events with infinite costs are hard to deal with: damned if you do, damned if you don't.
It's a bit like innocence and ignorance: once lost, they can never be regained. We're not going to lower our guard. We're going to keep nibbling away at freedom until, eventually, people get fed up with being oppressed and revolt and start the cycle again. We don't notice it happening so long as it's slow enough (just slow enough to go unnoticed by the majority,) but we still eventually feel it on our shoulders: the weight of our own collective fear dragging us down and holding us back.
Shall we call it the "cycle of fear and freedom"?