Bitcoin hitting $20,000 in the first day of 2018 is highly possible. The demand for Bitcoin is crazy right now. The supply cannot keep up with the demand and  people who also buys Bitcoin just hold it, that is why the prices of bitcoin are going through the roof. Of course  we  may see a minor correction every now and then but I am pretty sure that Bitcoin will continue to be bullish. 

I thought at first that John Mcafees prediction is crazy but with the price movement of Bitcoin right now it seems that he is right 1 million dollars in 2020 YES! It  can really happen.