His reasoning is that by definition speculative excess is irrational, therefore who is to say irrational markets can't get more irrational, particularly in the

His reasoning is that by definition speculative excess is irrational, therefore who is to say irrational markets can't get more irrational, particularly in the short term. In the short term markets are voting machines, in the long term they are weighing machines. Therefore shorting bitcoin is fairly stupid, as you can easily get run over and margin called or financially ruined if speculative excess continues and increases even if irrational. By going long, long term put options, unlike shorting a stock, on 5 year puts you a) cant get margin called and lose your shirt and b) They are long term enough that the whole speculative mania is likely to die down over time. And if it doesn't he would only lose the option premium, not an undefined amount of money. Finally, he considers assets that produce cash flows to be investments, while assets that don't (like gold, fine art, or bitcoin) to be speculation. And while there is nothing inherently wrong with speculation, he doesn't believe it is particularly enrichening either, and that purchasing productive assets is a far better use of his money. As a student of history, he has read about and witnessed many speculative manias that have ramped speculative assets (as well as investment assets far beyong anby rational value of their cash flows), and presumably think this one is likely to go the same way.