A fair point. It's been a while since then. I didn't recall that.
That said, he's just an easy example. There's a few other people who could be used. There's a billionaire who was an early Bitcoin adopter for example.
And it certainly would have been possible for Notch to become a billionaire without hiring people. The company only had 25 employees in 2014, and was doing $330million in revenue every year. There's certainly a path he could have tread to still becoming a billionaire without hiring anyone.
It would have been harder, taken longer, and not been as profitable for sure, but doable.