If he is already rich enough, he may not need bitcoin, although I find your argument too simplistic and I would like to know your friend's level of 'rich'. Do you know approximately how much wealth he has?
Anyway, it is a bad idea to try to change people's minds on financial matters.
You're right, buddy, trying to influence people's opinions about money is a bad idea, not to mention extremely dangerous. Rather than confusing someone about money matters, I will mind my own business because some people don't want to lose their money. Whether they are wealthy or not, I will never advise someone to invest in bitcoin. As for the friend's lack of interest in the cryptocurrency, I think it's a good idea because I don't know what he sees that makes him that way, and rich people don't even deserve to be advised to do so.
I said that the wealthy don't deserve to invest because a large number of them will not view your advice as sound, believing instead that you are trying to scam them. Wealthy individuals are extremely self-centered and always see the bright side of anything that comes from those who are not as wealthy as they are. I don't know about others, but I don't think it is appropriate to advise the wealthy.