None. That's why you don't get any money for filing a patent. In fact, it actually costs money to file a patent, so if you patented a "beard-extensions - like hair extensions for your beard!" or a "cheese-powered lamp", you're probably going to be poorer for patenting it. And since patents expire, you can make yourself very poor by patenting stupid inventions and sitting on them.
I've added no value, but I leave the patent office with a permit to use legal force against everybody that wants to use my idea. Nice, a real advantage for society.
Patents are not a magical money machine. They have no value unless they have patented an idea that someone wants to build and expects to sell for profit. And the government does not "assign" them a value.
Yeah, you need to apply that legal force for it to make money, I agree.
Your patent only has value if someone else wants to buy it off you in order to make the invention (or in order to sell it on further). And the specific value? Whatever the buyer and seller agree is the price.
That's the free-market way
It is not the free market way to grant privileges to a happy few. Government grants you ownership of something you clearly cannot own. You cannot physically own design concepts, as nothing is lost when I copy them. So stealing someones ideas, cannot actually happen in the real world.