I don't want read between the lines, but it's hard not to think it's a way for people to feel better about their own accomplishments by saying someone else had a massive head start.
Whether others do or don't, we should all be trying our best, be grateful for what we have, and proud of where we came from.
The money did come from something unethical--his family was enriched by segregation; racism; apartheid. That emerald money is dirty and is likely a key reason why Elon would deny its existence.
This brings us to the second thing: Elon lying about this. He has demonstrated that he is willing to lie about something this significant, which should do real damage to his credibility and trustworthiness if we are being logical and objective. What else is he willing to lie about?
And Elon was misleading and disingenuous but could still make a case that he hasn't explicitly lied on these things.
Ahhh, those historic pillars of morals and ethics, sub-Saharan Africa precious stone mines...