Unfortunately, most of his assumptions are based on traditional scarce assets, such as gold. Although I personally think that it will take some time for any altcoin to reach the height of Bitcoin, their functionality and practicality mean that it is entirely possible over time.
Why would you worry about that? It's not your money anyways plus he is a smart man and he knows the risk in investing money in bitcoin due to it's inherent volatility, now if he were to make it more than 10% if he decides to humor you, he would probably suffer a lot of losses. And the reason he is rich is because of those golds, they are more stable compared to bitcoin.