[ziddoap]

It's like spam.

Send out 1,000s of dubious demand letters which don't cost much. Some percent of those will settle with minimal effort on the troll's side. Profit.

Drop the ones that look expensive and hope they don't counter sue.

[HeatrayEnjoyer]

What would they counter sue for?

[ziddoap]

I probably should have just written "counter" or "fight back". I was rushing out the office door when I pushed the reply button.

In some countries you can sue for "unjustifiable threats to begin patent infringement proceedings", but I was also thinking things like filing complaints with the relevant Bar associations. That sort of thing.