Patent trolls typically have almost no overhead, just a small office in a cheap venue (Marshall Texas) and time.
Its simple math, 1) it’s cheaper to settle out then litigate (by far) so boards usually want to settle, and 2) its too expensive to litigate, ie you don't have 1-2 million to fully fight a patent troll.
Good for you for fighting. Ultimately thats what we've done and its the only way to stop the Trolls. (Shout out to Lee Cheng formerly from NewEgg)
There are some patent defense consortiums that you can join that will share the burden if you are sued by a troll making you a much less appealing target.
Good Luck!