With this approach to bitcoin, you can generally say the same about the entire cryptocurrency and even stocks in general. It seems to me that this opinion is not entirely correct.
Stock system in general have equity or capital. Capital can either be liquidated or used to produce goods and services and that's how the holders of stock certificates can return the investments in the system without new investors. Crypto is scam in general because it creates a system to lure people to invest and then people are able to return the investments only if someone buys the certificates of this system. Hence, a modern day investment scam.