Nowadays I'm running Firefox in my account as administrator. I've done this for years now. It would seem to me that setting my privileges to non-administrator would be a (major?) inconvenience. In Windows 10, wouldn't I have to switch users to do admin things?
It used to be (before Win 7 I think) that there was a way to run the browser as non-admin from an admin desktop. I think the term is sandboxing? This link might be relevant for Firefox sandboxing future possibilities:
https://www.currentresults.com/Oceans/Temperature/pacific-ocean-temperature-california-summer.php
I don't mind saying that when it comes to security I have a lot of insecurities i.e. I am no expert.
On a scale of 1 to 10, maybe I'd be at 7. But that is a log scale I think.