The point is to imagine what your life would be like if you didn't have to work for money. Imagine if you could work on startup ideas and software projects simply because you were passionate about solving a problem or creating something, and not because of the money. And it doesn't even have to be something useful, or something that people will pay for. You can work on literally anything you love doing, and you can find people who feel the same way.
That's the opposite of a "nine-to-fiver" who is primarily there for the money, although they might also enjoy the work.
Of course, you can be passionate about working on something while maintaining a healthy work/life balance. That's not really what people mean when they say "nine-to-fiver".