Explanation:
There are certain necessary conditions required for a market to operate as a monopoly. These conditions are not generally met in the real world. This is the reason why monopolies are very rare not so common in the real world.
A monopoly is a market structure where there is a single producer selling a product with no close substitutes. In the real world, almost all products have substitutes.
Also for a monopoly to operate there should be a restriction on entry and exit of firms which is difficult to hold in the real world.