Holding your own keys and holding Bitcoin means you own utxos. A billion people can't own utxos, it mathematically isn't possible.
Discussion
I guess I don’t understand. If bitcoin gets to billions of users then sats would be the standard for money and payments. There many trillions of sats.
That's not how Bitcoin works. You own utxos on chain and everyone can't own one.
Each wallet would have utxos. Anyone can have a wallet. Are you saying there is a limit to the amount of wallets?
No. There are limited numbers of utxos. Please read this posted link.
