The reason you can buy material goods with something as immaterial as bitcoin?
Creating bitcoins - rewarding miners - doesn't make the world richer in the sense of, with it, getting to have more material goods.
Money is just a medium of exchange.
Imagine it was God that told how much money each had.
Now imagine God would only make you have money if you helped maintain bitcoin, verifying transactions with your computer and the internet.
The world could be exactly the same, but now, just because God said, people that had computers and internet and were helping maintain bitcoin, would own more.
The world woudn't be richer or poorer. It would just have a different rule that was making owning different.
I once had a Cloak of Flames in Everquest.
I exchanged it for $1075.
That's a lot of apples!