Play doesn't have to be useless. It just has to be inefficient. Efficiency in this case would be to just go and buy an $1800 guitar pedal instead of investing

Play doesn't have to be useless. It just has to be inefficient. Efficiency in this case would be to just go and buy an $1800 guitar pedal instead of investing $40,000 worth of personal development time on a toy project for the sheer joy of it.