Let's say I created a system. Then I say to people: "invest your value in my system". And people do that.
Let us stop here for a moment. In your fictional scenario, why do you think people would "invest their value in your system"? I think that is an important part.
However, once people invested their value in my system I said to them: you are unable to return even a dime worth of value from my system, and if you want to return your investment, you have to wait for new investors to bring value into my system. Would you call me a scammer, and would you say that my system is worthless?
Yes. By luring investors with false promises about your "system," and later changing your terms, you would be considered to have deceived your investors, thus labeling you as a scammer.
However, I am not sure how this relates to Bitcoin in any way. Bitcoin, and the blockchain technology behind it, delivers exactly the "system" that people have been longing for. Ever since the introduction of Ecash by David Chaum in 1983. This particular "system" is the realization of a decentralized trustless system. This trustless system may not be perfect, but it does provide the ability to move funds without relying on any third party. It works regardless of the current value of individual units within the system.
So, if you have an idea for a better system, you are more than welcome to share it. Many have tried, and many have failed, but that does not mean that a new system will not replace Bitcoin at some point in the future. For now, though, Bitcoin remains the king.