Briefly explain Schumpeter's model of innovation. Why does an innovator's economic profit eventually reduce to zero?

Professor Schumpeter argued that the successful innovative entrepreneur's reward is a monopoly profit, which accrues because the entrepreneur is the first to bring a new product into the market. Having no rivals, that profit temporarily exceeds what can be earned under perfect competition. This high profit attracts imitating rival who "reverse engineer" the new product and are able to enter the market with their rival product and thereby erode the initial entrepreneur's "monopolistic" earnings. Eventually, those economic profits will be reduced to zero, because entry by imitators will continue as long as earnings are higher than that.