I agree completely, money isn't real, it's a tool for allocating goods and services, nothing more.

Let's take a very simple example. Let's say there are only two equal sized countries in the world and they both use the same currency (and only that currency) which has a fixed supply of 1 trillion units. Each of those units represents one trillionth of the total wealth of the world. One day one of the two countries decides that it will create it's own currency, also with a fixed supply of one trillion units. There are now twice the amount of currency units in the world, but the real wealth of the world hasn't doubled. Each currency unit now only represents a two-trillionth of the total wealth of the world, the original currency has been devalued by 50%. How this is perceived by people makes no difference, you can't perceive a new loaf of bread into existence when you only have one (without getting lost in metaphysics at least). Having an exchange to barter the two currencies with each other makes no difference, you have still doubled the total number of currency units, and thereby halved their value.

Of course the situation in the real world is infinitely more complex, and while crypto remains a tiny fraction of the world's money it's easy to imagine that there is the capacity for unlimited growth, but in reality the world is finite, the universe is finite, I think my fundamental point stands. If I'm missing something then I'd love to be enlightened.