If the skill set you offer is in demand and the pool of people is too small to meet demand you make a lot of money for that skill set. If the skill set you offer doesn't require much, something that anyone can easily pickup, and the pool of people to pick from is over saturated -- you get paid less for that skill set.
In actual reality, instead of hopeful, idealized economic bibble bobble, even skilled or in demand professionals get underpaid because the magical market for labor everyone conjures up in their mind palaces doesn't actually exist, and corporations collude constantly to suppress wages and even steal them.