In a democracy, we don't kill our opposition. If they hold views we don't like, e.g. that security trumps privacy, they're going to litigate them. Probably their whole lives. That means they'll keep bringing up the same ideas. And you'll have to keep defeating them. But there are two corollaries.
One: Passing legislation takes as much work as repealing it; but unpassed legislation has no force of law. Being on the side that's keeping legislation from being passed is the stronger position. You have the status quo on your side. (The only stronger hand is the side fighting to keep legislation from being repealed. Then you have both the status quo and force of law on your side.)
Two: Legislative wants are unlimited. Once a group has invested into political machinery and organisation, they're not going to go home after passing their law. Thus, repeatedly failing to pass a law represents a successful bulwark. It's a resource sink for the defense, yes. But the defense gets to hold onto the status quo. The offense is sinking resources into the same fight, except with nothing to show for it. (Both sides' machines get honed.)
Each generation tends to have a set of issues they continuously battle. The status quo that persists or emerges in their wake forms a bedrock the next generations take for granted. This is the work of a democracy. Constantly working to convince your fellow citizens that your position deserves priority. Because the alternative is the people in power killing those who disagree with them.