There're costs to that economic output that are not reflected in its dollar value.<p>For example, what's the value of having a parent at home full-time?  What's the value of having both parents home for dinner?  A bunch of studies have shown that one of the best predictors for having successful, well-adapted children is how much time the family spends together.  But how do you quantify that?  You won't know what the exact payoff is until 10-15 years later, when the kids are well into their own careers and having their own children.  And it varies a lot from kid to kid - someone who's performing well academically with a supportive peer group needs a lot less parental involvement than a loner with no friends who's threatening to blow up the school.<p>Or another example: when I went to college, I believe the fin-aid formula was that the college would take 100% of my assets, based on my age and income.  That meant my gap year was revenue neutral - it didn't matter how much I worked or what I worked on, I wouldn't be able to keep any of it.  But that gave me the freedom to observe and to try things out, without the stress of trying to make a lot of money, and in the process I found my eventual career.<p>You don't want to run an economy like this - there needs to be some accountability so that people work on things that are actually useful.  But a high school grad who's time-limited to one year of work isn't going to accomplish anything actually useful anyway - instead, that gap year is an investment in perspective, a way to understand more of the world before you commit to four years in college.<p>The same thing often comes up in research - a short-sighted focus on increased economic output leads you to miss opportunities that have no obvious dollar value attached, but can be big economy-changers in the long run.  How long did it take GMail to become profitable, and would it have existed had Google had the same quarterly bottom-line orientation that most public companies do?  How about Google itself?  If Larry and Sergey had done the economically rational thing in 1995, would we still be searching on AltaVista?  Is Twitter making money yet?