In the end this depends on your definition of "fair". What percentage of your generated production do you think is fair for the company to take? 95%? 50%? 10%?
Can an employee obtain better employment terms elsewhere (which is a complex concept to define in itself)? If so, they are underpaid, if not, they aren't.
What's the point of inventing a non-existent situation where you're obviously correct, other than self-gratification?