Perfect competition is one end of a spectrum, where the other end is monopoly. Monopoly is a stable equilibrium, whereas perfect competition is not. On a long e

Perfect competition is one end of a spectrum, where the other end is monopoly. Monopoly is a stable equilibrium, whereas perfect competition is not. On a long enough timeline, a perfectly competitive system will decay into a monopoly and stay there unless acted upon by an outside force designed to break up the monopoly.