Interesting. My memory is probably hazy, but for me, Chrome took off because the choices at the time were IE and Firefox, which used to be an insane memory hog.
That was Opera. Chrome took off because it was and is advertised on any Google property.
Chrome took off because it had the ability to not take 15 minutes to cold boot during the era when firefox did.
I've been using Firefox continuously as my only browser since it was in beta and called Phoenix. This has never been even remotely true, at least on my experience.
To carry on with your anecdotal evidence, I'm going to disagree and say that yes, there was a time where firefox was just dog slow to open - on all 3 of the PCs I owned at the time, two using only 2-3 extensions and one using none. If there wasn't, I never would have switched to chrome.
IE was pretty bad but Firefox was decent. I interfaced a bit with the early Chrome team. Better performance was a necessary but not sufficient condition for success. Chrome was the fastest browser for at least six months but many early adopters wouldn't touch it without an extension framework. Certain extensions like Firebug had become extremely popular with developers by then. Google wanted these developers as early adopters. Once the extension framework was released then everybody hopped on the Chrome train (except for the Firefox purists), and Google proceeded to leverage their O&O sites (and spend billions of additional dollars) to pump distribution. Later on the extension frameworks (for all browsers) became riddled with malware and adware and are still a major source of vulnerability today.
Great point about Firebug. I can definitely remember using Chrome for pleasure and Firefox for work for a time.