Painting this as something to do with greed is wildly off base to me.
meno, the salary cap itself is a function of owners worth billions of dollars artificially setting a ceiling on the marketplace for labor. It is greed.
I have no side to take, nor bone to pick, but looking at it like an economist would, there is no supply and demand market for labor like in the rest of the world. There's basically a monopoly and monopsony, and nobody gets paid what they're worth because of market distortions in the name of franchise fairness and keeping costs down for the "lower revenue" franchises.
It's a distorted market right away with the draft, and continues to be so under the CBA. Courts haven't gotten in the way only because the league makes compelling arguments that the restriction on labor is necessary for league survival. That and other technical legal doctrines that I forget right now.
A good sports lawyer would know why they're not in violation of basic anti-trust and laws that ensure eighteen year olds have the right to seek employment without artificial barriers to their procuring of said employment, but I don't at the moment even though I took Sports Law in law school. I've forgotten the technical arguments of law behind the courts' reasoning.