The "laws of supply and demand" are not empirical laws of physics. They are general principles with well-known exceptions and flaws of their own. You should lay off the microdosing.
If a vendor anywhere in the world has more stock than their customers want, the price goes down. If more people want it than the vendor can provide, the price goes up. If there's more food than animals that want to eat it, animals eat their fill and the rest rots. If there are more animals than food, each spends increasing effort developing strategies to get more than their neighbors.
Now, if someone claims they can prove that demand increasing by X results in prices increasing by exactly Y, I'm with you. There are too many variables to make that predictable. But the basic idea behind it? That's pretty fundamental.
Game theory is mathematics, not science. You can derive the basics of supply and demand from game theory.
Economics is a soft science. But so is history and, I'd argue, a good deal of computer science.
You can derive supply and demand from game theory once you make some assumptions about preferences, costs, rationality of players, etc., all of which are non-mathematical, mostly empirical concepts.