Well, we all have different opinions on Bitcoin which is actually normal. Even if you say that there are only a few people holding Bitcoin, the market still depends on its volatility Bitcoin's potential for the long term for sure would increase its value but its current value would be volatile. If your friend is already rich and doesn't want to invest in Bitcoin, I think it's more like his preference, because he might get rich in another way cause if he'd make money in Bitcoin, he wouldn't doubt it. Some rich people find alternative investments other than their source of money like from their business than putting them into a bank. I also think that your friend might not be knowledgeable enough in the crypto industry but has other ways of making money where he's much more skilled and smart.