Doing what you love / care about, at least partially, while still making a living is an interesting task. Also a highly nontrivial one unless/until you've already made a few millions.
One way to do this is instead of watching TV, playing WoW, etc, that is, instead of pleasant but exclusively consumer activities. Seen at this angle, the advice does not look all that bad.
This is not unlike having kids. You don't quit work to have kids; to the contrary, you work harder to give the kids a head start (nice toys, good books, advanced kindergarten). You don't stop working for money, but you spend the money for what you love more than money. If this works for your child, it could also work for your brainchild (which is often less demanding, too).
Not everybody's passions are monetizable and produce items or services desired by a market. One cannot make a living making esoteric GIF art. No amount of staying up late and working hard makes this true.
It's not like I choose to watch TV at night instead of building some dream lifestyle business.
How would you propose I monetize creating my own free open-source programming language? "Just don't play WoW" doesn't make sense in these scenarios. Contrast that with the passion of "publishing books". Starting a publishing company would be an obvious choice.
I think you define passion too narrowly. It's hard to monetize your passion if the only thing you enjoy is drawing pumpkins with charcoal on the walls of 18th century buildings.
But flexibility helps. You could, for example, make a living working on V8 or SpiderMonkey, and work on your programming language as a hobby.
One way to do this is instead of watching TV, playing WoW, etc, that is, instead of pleasant but exclusively consumer activities. Seen at this angle, the advice does not look all that bad.
This is not unlike having kids. You don't quit work to have kids; to the contrary, you work harder to give the kids a head start (nice toys, good books, advanced kindergarten). You don't stop working for money, but you spend the money for what you love more than money. If this works for your child, it could also work for your brainchild (which is often less demanding, too).