What's best for consumers is having a variety of competitive choices: in the short term a monopolist can offer the 'one true best option', but over time they (l

What's best for consumers is having a variety of competitive choices: in the short term a monopolist can offer the 'one true best option', but over time they (like all companies) will stop acting competitively and then consumers will be harmed by the lack of other options. That's why it is bad for consumers when monopolists emerge: during the emergence they likely do benefit, but it can take decades for a market to recover once the monopolist stops being competitive.