What browser do you use on mobile that has noscript sync with desktop? You make it sound like it's some feature other mobile browsers have that Firefox is missing.
I've been using it for various reasons for about 15 years. So "familiarity" is one of my main reasons now, but a big part of it is to avoid being advertised to in my OS.
I've been a fan of FOSS for a while, but the big thing pushing me even further is the fact that commercial services are adding so much advertising and data tracking. I'd happily pay for a piece of software that works as promised and does not include advertising, but when you start throwing ads in my face or putting features behind "IAPs" and subscriptions, I'm going to look for alternatives.
That... is not at all specified what kind of "mine" it would be. You're assuming it's innocuous, everyone else is assuming it's malicious. But we're all making assumptions.
Or I could just... buy a laptop that doesn't have an expiration date.