If I run around town smashing windows with a rock, GDP goes up. Computing value more accurately than financial markets is not difficult: the bar is on the floor.
Breaking windows DOES increase GDP, just like the parent said. The argument ( https://en.wikipedia.org/wiki/Parable_of_the_broken_window ) only argues that not all GDP increase is good, because of waste of resources, because of the opportunity cost. That's why measuring success only by GDP is a bad idea.
