The answer to this question is of course No because older people don't know how to buy and sell Bitcoin they don't know what is crypto so this is impossible, also some people think that crypto is haram but in real crypto is halal. that are 2 big reasons and some are too much poor so they cant buy BTC.
You have replied to the above post in a context that is quite different from what the Op intended. The creator of the topic was wondering how possible it is for the 21 million bitcoins to be sufficient for every human being assuming they are all to acquire bitcoin. Also emphasizing that there are people that are holding much bitcoin and are unwilling to sell which will make it impossible for everyone to own a few sats of bitcoin.
My straight forward answer to OP, is that everyone in the world cannot own bitcoin as of now. Assuming it can be reversed that all lost bitcoin be restored and all everyone holding bitcoin should sell and bitcoin goes back to 21 million. Then, bitcoin will be sufficient for everyone in the world.