[equity]

Although trolls are lawyers, there is still a "cost", and in this cost is time and the opportunity cost of spending time elsewhere. Going to court, getting a judgement and collecting fees is a huge time sink. Patent trolls are not dumb. They will litigate when you are a big fish.

[brazzy]

Or when they want to keep the threat of litigation credible in order to extort out-of-court settlements.