Rule of 3 (market structure)

Biological Parallel

Competitive exclusion principle states that competing species cannot stably coexist on identical resources—yet ecosystems routinely support 3-4 apex predators through niche partitioning. Lions hunt large prey in daylight, leopards take medium prey at night, hyenas scavenge and hunt in packs, and cheetahs sprint for small prey in daytime. Three is the minimum for true diversity, the maximum before niches become too thin to support viable populations. Markets stabilize at three for identical reasons: fewer collapses to monopoly, more fragments into unstable microniches.