You ignored the entire point. So, I am going to make it easy for you by asking you one simple question: can anyone in the bitcoin scheme benefit from the scheme without new investors entering the scheme?
Yes you can benefit from it since it is NOT a storage of wealth like so many idiots in this forum believe, but it is a decentralized currency that you can use to send payments.
You're supposed to explain HOW holders can benefit without new buyers - investors, not talk about concepts. Try again. P.S. "A payment" is a new buyer entering the scheme. The question is how holders can benefit without new buyers entering the scheme.
You can benefit from the security and the anonymity of the system. One crypto owner can buy a good from another crypto owner and therefor both benefit from the bitcoin system. There is no need for a new buyer to enter the bitcoin ecosystem.