Microsoft was ruthless and technically competent, but in many ways they were also strategically stupid.
- IE was a Windows-only product (after Microsoft dropped Mac support), so as Windows lost its dominance (thanks to the internet, and mobile devices, and Linux, and Apple's rebirth, and...), so did IE. It helped sow the seeds of its own destruction.
- Chrome has an open-source core, so they're going after the embedding market much more than IE ever did. That means that a lot of "Chrome" use is in places where users feel the consequences, but have no control over being able to switch engines (e.g., Electron apps).
Google's web browser group feels like the classic "big, smart" quadrant competitor that nobody will engage. If your only goal were "take over the world usage share of browser engines", it's hard to imagine doing a better job than they're doing now.
The client-side web was not traditionally Microsoft's home. They were a little late to the game, they didn't quite understand it, and they needed a good browser on their platform but it wasn't fatal if it wasn't theirs. (They're doing quite well in services and games and many other areas.) Google was always web-first, and they will never cede that.
Crazy tech prediction: Chrome will be the last dominant web browser engine. What defeats it will be the successor to the web, not another "web browser". Its successor will probably even embed Chrome for backwards compatibility, like Edge embeds IE, or Chrome embeds FTP. We'll look at legacy Chrome-compat internet sites the way we look at Electron apps, or non-TLS websites.