And why is it wrong to think it might take a couple years to see a return on your investment? In what world would investments immediately pay dividends? Most people aren't living on 45k (take home), and if you told them that they could do that for 4 years and then be living on 100k take home, they'd be very happy.
The issue isn't "time to return." It isn't even "degree of return," which, as vanwinkle rightly echoed, can very well
be 0 if you don't make partner. It's "kind" of return. We have this idea in our society that there are right ways and wrong ways to make money. While it might not be illegal, the way law schools make money may well be morally wrong. To state it in one sentence: law schools make money that other people earn. In another thread, I called it "rent seeking."
Your return isn't going to be $0 if you don't make partner, that's ridiculous.
. 3-4 years is a long time. If you're not on the partner track, by the 3rd or 4th year, you're not getting the assignments you want, you perhaps have already been told to look for another job. Let's just switch gears for a bit and ask an overview question: how many associates, who are not these newfangled "career associates," have 4 years in and are not in the running for partner? Someone can answer that...
Even if you get pushed out after four years in, it's not like you exit into the same job you would have had pre-LS, or even the same job you would have gotten without doing big law first. Your return will be positive to the extent that this job pays more than you would otherwise have made.
I've done this analysis elsewhere, but I'll recap it here. The long-term trajectory of former big law attorneys will be: in-house, to partnership at a big firm, to a small firm, to government, to solo practice, or out of the law. Let's look at how many attorneys are in each of these categories:
There are about 65,000 partners in the NLJ 250.
There are probably 30,000-40,000 in-house positions at Fortune 500 companies.
There are about 32,000 lawyers in the federal government.
The first two categories will tend to grow with GDP. Even in this weak economy, GDP is growing at roughly 2%. Let's assume the latter won't be growing at all for the next decade. On top of that, there is some natural attrition from retirement. Let's say 2.5% (a 40 years beyond time spent as an associate). That's roughly 5,250 new jobs opening up each year from growth and attrition, using extremely conservative estimates. There are roughly 5,000-6,000 new attorneys joining big law firms each year.
Essentially, the big law sieve along with the tendency of in-house/federal government employers to hire out of big law makes the post big-law employment situation very different from the post-JD employment situation.
 An Altman-Weil/Lexis/Martindale survey found about 3.5 in-house lawyers per billion of revenue (http://www.inhouseinsider.com/
); the F500 had $10,800 billion in revenue last year.
 http://www.washingtonian.com/articles/p ... are-there/
 This estimate is almost certainly too low. Law firm partners spend 8-10 years as an associate first, which means their career as a partner is probably more like 35 years, even if they retire at 70. Federal government pension eligibility means that most will retire at 65 or earlier. Indeed, federal agencies like the FCC are on the precipice of mass retirements: http://www.federalnewsradio.com/?nid=520&sid=2834000