According to the 2011 Statistical Abstract, legal services in 2007 reported gross receipts of 267 billion dollars. Students view it as a wise investment to incur debts on average of $100K to go to law school for the chance to assume roles in the legal system.
If we assume people to be minimally rational, such investments are reasonable only if we believe law serves a valuable purpose, one that merits our money and, for many, our lives. Efforts to describe the details of that importance, however, can be exasperatingly vague.
Donovan, James, "Why Law?" (2011). Law Faculty Popular Media. 54.