There's nothing imaginary about fairness. It's an evolved response to resource misallocation in herd animals, including primates.

http://www.livescience.com/26245-chimps-value-fairness.html

What's imaginary is the idea that competitive advantage is always a good thing. The reality - as you say - is that too much competitive advantage leads inevitably to logistic collapse.

In humanity's case, the logistic collapse regularly leads to cultural extinction, and it's not impossible now for it to lead to physical extinction too.

The real problem is that competitive advantage is a very poor substitute for collective intelligence. we have an economy of competitive individualism, but we've yet to imagine an intelligence economy where growth is explicitly measured in increased collective insight and foresight.