He is including all time spent learning stuff and so on. 40h work + 40h learning/reading HN/doing hobby projects is pretty common.

Is it really? That's 16 hours of work 5 days a week. If you sleep for 8h you don't do anything but work or learn for all of your waking hours.

A more reasonable person would probably put a fair amount of learning time on the weekend, but even then you leave very little time for a social life, physical exercise, eating, relaxing.. things that most healthy people, if not everyone, requires.

Working 40 hours per week and sleeping 8 hours at night leaves you 72 hours of free time a week so you still have time for other activities.

Also, learning and hobby projects can include social aspects.