The patent trolls don’t. And neither do the courts. Is it moral for costs to rise into the multiple millions merely for bringing a patent troll to trial? Or how about the $30 billion per year costs of patent trolling to industry?
The FTC has supposedly been investigating patent trolling since about two years ago. Meanwhile, the incidence and costs continue to climb. This is called “lawfare”, or the deliberate jamming of the legal system in order to paralyze it.
It seems you are forgetting many people in your analysis. The most important of which seems to be the original holder of the patent who receives money from the troll. Those people are legitimately helped by the troll.
Two words on how to put a stop to this: Loser pays.
The reality is every company is a troll in some instances. The majority of companies have patents that cover ideas that are never incorporated in products, and so if they ever assert these, then they are a troll. Similarly, every university functions essentially as a troll with their patent portfolio.
The other truth is that without trolls small inventors would have no market in which they could sell their ideas. Without this market, big companies would be free to steal the ideas of small inventors.
While trolls aren’t perfect, they are much better than what would happen without them.