You were saying "1 hour a day!" and then mentioned a guy who didn't work anything close to full time at a paying job for nearly 5 years to work 12 hours 7 days a week on something that _might_ pay on release..
He worked on something over a long period of time knowing simply that it's OK for something to take time to complete. He understood the challenges ahead and planned his days accordingly.
The point of the Steph's article isn't to only think inside of eight hours, but to think about time management, patience, focus, and other key aspects as a whole, to get the better picture of the path forward.
It doesn't matter if it takes four months or forty years to make a project: it's making it that counts.
The unknowns where how much time it would take a single developer to make such an ambitious project and the degree of the payoff.