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I do not believe he shorted, as he also invested in Miraiex. Shorting bitcoin and longing an exchange could be a trade but.. Mostly game theory and opportunity cost: You have to invest to not risk being priced out of the potential new economy/ paradigme.

Great tought! Tested Miraiex?

No. I have just used "foreign" exchanges like Binance, Bittrex, Kucoin etc.