He also called it an angel investment. As in 1/10 or 1/20 chance at profitability, and less than that at long term sustainability. Though at this point I'd consider buying bitcoin equivalent to buying stock in a company with a promising product but some major obstacles to achieving its vision. It could go to the moon if things work out (Facebook). It could muddle along if it has a brilliant idea but major internal problems (Twitter). It could go to zero if people lose interest, lose faith, or an amazing competitor comes along (Yahoo search).