He said back in December the price of bitcoin would collapse.  He built a pricing model using the adoption rate, money supply, and other factors and calculated a forecasted weighted average value.  Current bitcoin prices of $9000 US, he says, suggests an adoption rate of 40% for bitcoin and a 25% likelihood of it happening.  He sticks by his thought that adoption will not occur near this rate, therefore, the current valuation should be around $500 US.  If you are buying it, you are expecting growth in the adoption rate.