It is not wasteful, it is a must. You can't create money out of thin air like fiat money, that kind of scam must stop, this is the point of bitcoin
Doesn't Bitcoin do the same - creates money out of thin air? Why the current reward is 25 BTC instead of 17.82 BTC?
Just like digging out gold, it seems the labor wasted are unnecessary, but it does solve the origin of value problem: The man who create money must pay fair price to get it, otherwise everyone will be just creating money and no one will be working
A currency's value isn't defined by how it was created, but it is defined by its utility to the currency user.
I fail to see your logic of "the man who create money must pay fair price to get it". That is a subjective statement. A "fair price" is defined by what the market is willing to pay vs the perceived utility of the item being sold.