He does put caveats around his initial, condescendingly worded points. The problem is that those caveats are either too small, or they completely contradict his initial point.

Again, if all it takes to become a billionaire is 15% growth rate for 5 years, which is easy, then if you start with two billion dollars and grow at 15% per month, you'll be a trillionaire in 5 years. And 5 years after that, a quadrillionaire. If the billionaires are literally generating billions of new value, what explains why trillions can't be generated in the same way?

If the market is limited, then it means that you can't grow your way to a billion dollars, you have to displace others - either competitors in the same market, or other markets as well. So now there's a much clearer chance that you're using underhanded means to actually get your billions - you're not growing a new pristine market that people just love, you might just be edging out competitors or snuffing out other markets that had existed before - and perhaps were limited by things like regulations or externalities that you simply choose to ignore.

And the question of externalities and unfair competition and corruption is not tangential, it is the whole point that Alexandria Ocasio-Cortez or Bernie Sanders or others in this anti-billionaire movement are making. Not talking about it is simply ignoring their argument. The problem isn't "oh, I didn't realize that simply growing at 15% every month for 5 years will make a million dollar business into a billion dollar business". It's "the actions that you need to take in order to continue growing at 15% every month for 5 years are going to include things like un priced externalities, corruption, cartel behaviors, etc". Addressing how you can sustain this growth, and how the markets can have so much money in them, are exactly the most important things - not the trivial math of exponential growth that he discusses, condescendingly, at length.