For the same reason that lawyers took the case Kouichi Taniguchi v. Kan Pacific Saipan, Ltd, 566 U.S. 560 (2012), a $5,257.20 bill of costs dispute, to the U.S. Supreme Court. (A discussion of the lawyer's motives in that case can be found here.)
It was what is called a "test case", where the stakes in the particular dispute are low, but the legal principle to be resolved has broad application to many disputes large and small.
This kind of litigation behavior (i.e. spending far more money litigating a case than the individual dispute merits) is sometimes called "strategic litigation" behavior. Sometimes that term is referred to in the sense of a pattern of litigation designed to promote human rights (synonymous with "impact litigation"). But, the term is also used more broadly, to refer to any lawsuit brought primarily to set a precedent rather than due to the stakes in the particular dispute at hand.
"Tactical litigation", in contrast, is used to refer to the practice of pursuing a lawsuit because it will delay some action from being taken or make it costly to do so, in which the litigant doesn't care about the outcome on the merits, which is in some ways the opposite of "strategic litigation" in which the outcome on the merits has greatly exaggerated importance relative to the dispute in question.