> Do the browser elves carry out secret overnight installations?
Actually they do (especially some years ago).
I manage, like most, computers of older or computer-challenged family members, and having them all staffed out with Firefox, I found them every week browsing in Chrome, over and over again. Don't you remember, at that time a staggering amount of installs and updates did also made a stealth install of Chrome and made it secretly the default browser.
How do you think Chrome became overnight the majority browser? It wasn't that good... But it did shamelessly commandeer the computers of millions of unsuspecting people who never noticed the difference.