People choosing to not use other options that are easily available doesn't seem like something that should qualify Google as a monopoly that needs to be broken up (am not a lawyer, just a disclaimer).

Like, what is Google supposed to do here? Make their own search engine worse, so that users are incentivized to switch? Show people ads, recommending them to use competing search engines?

Mind you, I am not alleging that Google is not a monopoly or that it shouldn't be broken up. There could be other things that could qualify them for that, like bundling of Google Search as the default search engine with Chrome, semi-mandatory nature of Play Store on android just to be able to use google apps, etc.

However, just the sheer fact alone that most people prefer to use Google search (when there are plenty of easily available alternatives out there that the general public isn't willing to look into) shouldn't be valid grounds for an anti-monopoly lawsuit.