This article reads like a rather flippant dismissal of the original concern that "earning" a billion dollars cannot be done without some moral compromise.

Sure, if you start off with $2 million and double it 9 times, you end up with $1 billion. Exponential growth is a powerful thing, so it comes as no surprise that maintaining a large growth rate over time very quickly grows a starting sum into a much larger pool of money.

However, his only response for how you should achieve exponential growth is this hand-wavy "make something you yourself want". His only acknowledgement of the concern that maintaining exponential growth may require cheating is a casual dismissal, and his only acknowledgement of the concern that the growth rate will drop off over time is "you'll still get there eventually".

So, while the original concern was that you cannot earn a billion dollars without some wrongdoing, PG's response can be boiled down to "nuh uh".