You're 100% right. For years Firefox was really the only game in town that was competitive with IE. Even Mac OS had a "IE for Mac OS" because otherwise the Internet (mostly) wouldn't work on a Mac.

By the time Chrome was released, Google basically had to explain why they were creating their own browser given that IE, Firefox, Safari, and other browsers (WebKit was a fork of KHTML from KDE) were already available. At the time, they justified it with performance enhancements and a different process model for Chrome. There was a good case to be made and Chrome was indeed faster when it was launched.

It's pretty obvious at this point that the only business model available for Google and most of the other big tech companies is to hoover up your data and use it for the presentation of ads. If I were a more of a conspiracy believer (or even thought that Google had some foresight), I would think that the only reason Google launched Chrome was to eventually do away with ad blockers.