I can only think of one thing, Peter Schiff is still living in the past and he still hasn't been able to understand and read that Bitcoin is the future unlike Microstrategy.
He didn't come up with a revolutionary theory, Microstrategy's buying rate of Bitcoin is definitely not sustainable, they won't buy forever, they will stop at some point and start making their profits, but what will he do then?
If he doesn't like Bitcoin and doesn't understand it yet, he doesn't have to buy, no one is forcing him to do so, he should simply shut up and let people do what they think is right for them.