With the end result of enshittification, people will migrate if their experience is bad enough. Google wants to strike a balance between making as much money as humanly possible and making the search experience at least decent enough to retain the majority of their users.
True, if you look at YouTube, it’s been getting worse and worse over time and yet people still go there, but that’s also due to there being not that many good alternatives that have a bunch of content. Google has a ton of other good alternatives to compete with, so they’re betting on the laziness factor and probably that people don’t know better.