a legal battle is a battle to the death where there are no rules. You need to do what it takes to win. If you lose, the results can be very bad for you. And you can lose a lot of money.
The original idea was from Red Hat where it is just better to settle than to fight. Here the lawyer says, look at how much time and money it will cost you and if it is too much, then settle. Now it is an accounting issue.
With the same reasoning, why send people to jail? The crime has already been committed and going to jail will only cost the public money, and not change anything. Cheaper to say the accused was a bad boy.
We have jails to act as a deterrent. You fight lawsuits to make it clear to other patent trolls you will fight in court and not give up when you are served the legal papers.