Question

Economist claims that the equilibrium position of each firm in a perfect competitive industry the equilibrium can be at the point where D= P=MR=AR.At that point , you can notice that the equilibrium market price average revenue per unit is exactly equal to the average cost per unit.this means that AR*Q is exactly equal to AC*Q which means that TR is the same asTC.since cost and revenue are the same , this means that there is no profit.so why would any producer stay in business if there is no profit to be gained from doing so? your explanation should be supposed with a graph for more detail.