I think one of the method you can adopt to convince him is explaining the practical aspect and benefits of investing in Bitcoin, one of the ways is physically showing him your own Bitcoin in your wallet and how it price had been increasing during bull run as well as exchanging few of your Bitcoin to fiat in his presence thus to let him know that virtual currency is also a real currency with that you would be able to convince him that investing in Bitcoin is not a ponzi scheme and not a scam and encouraging him to start with small investment first by creating a wallet and sending the coin into his new wallet just to have feel of real live investment in Bitcoin and I believe with time he would change his perception about Bitcoin.