Usually when a monopoly that isn't a natural monopoly is broken up,the losses to the producer outweigh the gains to consumers.

Breaking up a monopoly can lead to more competition, lower prices, and increased innovation, resulting in overall gains to consumers. While the producer may lose its monopoly power and some profits, it can still benefit from operating in a more competitive market. Additionally, breaking up a monopoly can lead to the creation of new, smaller businesses, which can also benefit the economy.