I understand that block rewards are made out of nothing but say a miner wants to cash out on all of their bitcoins... this will lead them to obtain, let us say, the USD equivalent of all the bitcoins the miner has from transactions + whatever the miner earns as block rewards.
So what this is doing is giving the miner all the USD they legally own and also some extra money that they generated from their block rewards. How is this legal because no entity is paying the miner and the miner is technically making money out of thin air?
I know this is kind of a complicated query but I do not understand how it is okay to make money out of thin air like that.