Do you have any data to back that narrative? I know Mozilla is pushing that explanation, but from how I remember it Chrome gained market share because it was technologically superior to Firefox when it was released. It had a much more modern UI, much faster JS implementation, sandboxed tabs, etc. All features that it took Firefox years to copy. Some would say that Firefox has never caught up.
I find the ads narrative pretty hard to believe. Back in the days, Firefox could compete with IE, which was the default in Windows, by being technically superior. It seems very likely that Firefox's users, who had gone out of their way to install Firefox, would also be very willing to go out of their way to install a new better browser even in the absence of ads.
