Well, show me a perfect metric that doesn't have similar edge cases? For example, income has its own issues -- a retiree can have little income but a big retir

Well, show me a perfect metric that doesn't have similar edge cases? For example, income has its own issues -- a retiree can have little income but a big retirement fund to draw down. In an ideal world, you'd probably measure something like current net wealth + discounted expected future earnings, and maybe use PPP instead of GDP, except now you're trying to measure two things accurately instead of one, and making guesses about the future too.