There is several kinds of abuse going on:
- antitrust abuse, in that Google is cross-subsidising spending billions of dollars per year on a free browser, pulled from revenues from their dominant market position on search advertising (and then setting the default search engine to re-inforce that dominant search position)
- dark patterns where Google both sneakily installs Chrome with lots of other programs even if the user doesn't want it, as well as popping up banners on Google properties that suggests that your computer doesn't run properly without Chrome (yes MS does it too, and no that doesn't make it right)
- repeated so-called "bugs" where Google 'engineers' slow down Youtube or Gmail massively on rival browsers by exploiting minor differences in Javascript interpretation for plausible deniability