One thing I think I've underestimated is the extent to which the "prestige" associated with being a lawyer affects peoples' thinking about whether to go to law school. This thread on TLS features an OP who, less than a year out of undergrad, is making $60K at a consulting job which features a lot of career stability, that will be paying him around $80K in his mid-20s, and around $100K by the time he's thirty, and which has ceiling of around $250K long-term, although it sounds as if he's more likely to top out at around $150K-$175K on this career path. He's bored by the work (which in comparison to being a lawyer sounds neither particularly stressful nor time-consuming), and he doesn't like the fact that no one seems overly impressed when he tells them what he does for a living.
The OP is quite refreshingly straightforward about his reason to go to law school: to make a lot of money, and to have a more prestigious job than being a consultant. His plan is to go to a lower T-14 and via a combination of "scholarship" money, family help, and savings, graduate with no more than $100K-$125K in debt. He'll then pay this off by working in big law for a few years, then lateral into an in-house position. (He's got a 3.5 and a 170, which would probably require him to pay sticker or close at lower T-14 schools, and which would leave him with far more debt than this, but he plans to retake the LSAT, add a few points, and shake some money out of Michigan or Penn or UVA or whomever).
His thinking is that the in-house position will in all likelihood pay enough to justify the direct and opportunity costs of going to law school, and that there's a decent chance he could get a post big-law job that would pay a lot more than $250K per year, thus making his law degree a good to excellent investment.
From a purely financial perspective this is, to put it mildly, a terrible plan -- his realistic best-case scenario is that he ends up more or less breaking even in the long run after dropping $500K in direct and opportunity costs by going to law school, and of course he's running a huge downside risk. So why is he even considering it? This is somebody trained in quantitative analysis after all, who is paid to advise business people, so it's not as if he's an innumerate snowflake who doesn't even know what "opportunity cost" means.
Who knows, but my guess is that what this guy is really chasing after is the cultural prestige associated with being a lawyer. When push comes to shove he's willing, or thinks he's willing, to take what from a probabilistic standpoint is a ridiculously risky gamble, in exchange for being able to tell people he's a lawyer.
And that, in the end, is what law schools from Yale to Cooley all sell, in one way or another.