perhaps i'm reading it wrong, but seems to me he's being sarcastic when saying"the smartest people will short"... that if the rest of the world keeps pushing the price higher, these "smart people" in their short positions will get squeezed...
the potential upside seems unlimited, the potential downside is only 100% but if you leverage short, your potential losses are seemingly unlimited... risky position to take perhaps
RE: Bitcoin Bears Unleashed? Interactive Brokers Folds, Will Allow Clients To Short Futures