Short-Run vs Long-Run Outcomes
In the short-run, firms in monopolistic competition can actually make supernormal profits - just like our successful pizza shop that's found the perfect recipe and location.
However, the long-run tells a different story. As industry supply increases from new entrants, each firm's demand decreases, shifting the AR (Average Revenue) curve to the left. This continues until firms only make normal profit, where P = AR = AC.
Here's the crucial bit for your exams: monopolistically competitive firms are neither productively efficient (not producing at the lowest point of AC) nor allocatively efficient (price doesn't equal marginal cost). They sacrifice some efficiency for product variety.
The end result? Consumers get more choice and innovation, but pay slightly higher prices than they would under perfect competition.
Exam Tip: Remember that long-run equilibrium always leads to normal profits due to easy market entry!