If you were in his shoes, can you declare your crypto asset to your family? Or do you think he should have declared it to them after the extended family members must have left and even if he did, the information can still leak to the extended family and from there it can escalate to other people. What opinion do you have to give in this situation?
No matter the pressure of any of his relatives should he expose his portfolio to them just for the sake of proving his doubters and their critics of his investment plans and portfolio.
Infact, the inquisitiveness of those his family members should ought be thoughtful if they've ulterior motives towards his claimed assets on bitcoin. Remember, only those who knows your Worth are ones to think evil of you which is equivalent to say that even if the family doesn't mean you a harm, it's still necessary to avoid future occurances that may hurt us whereby in this case, any of your family members amidst the discussion may turn against betraying you for selfish interests.
So, he should keep mute and chase his dreams. Family will always welcome you and even summons apologies over treating you in the past while you were poor.