I noticed that I never reported the results of trying to un-learn the use of Invert Mouse.
After about two weeks, I was no longer fighting my muscle memory and could play MMOs unhindered.
After about a month, I felt like I could aim pretty well again in shooters where precision is important.
It’s now been nearly six months, and I feel like I’ve never played any other way.
So it is possible to switch, even if you’ve played with Invert Mouse all your life. I have not attempted to play any flight simulators since switching though. I suspect I would crash and die instantly if I did.