The system
While many boosters of free market capitalism like to portray it as a force of nature, it is in fact only one possible system of organizing economic activity. To go beyond that religious faith to something approaching science, evolution (the real thing, not the "Social Darwinism" travesty) teaches us that success is determined by ability to adapt to local conditions.
No matter what the system, it will produce winners and losers, and the winners are those who have merit as measured using only the rules of the local system.
Every economic system is a meritocracy. They differ in how they define merit.