One additional cause of new Chrome installs taking over from Firefox: bundleware. Chrome is foisted upon users as install-by-default bundleware when users install or update lots of different apps, especially free antivirus apps on Windows. Just clicking "Continue" when your free antivirus on Windows updates will cause Chrome to be installed and set as the default browser. Here's an image of Avast tricking you into installing Chrome: http://imgur.com/hNZLbmL
I've had to fix this for three family members previously as they were using a free antivirus and couldn't figure out why their browser looked different and didn't have an ad-blocker now.
I've had to fix this for three family members previously as they were using a free antivirus and couldn't figure out why their browser looked different and didn't have an ad-blocker now.