I am on my 3rd Model S.
1st car was in 2016 Model S, got the FSD then, but the car was close to 100k, then did a 2k CPU upgrade to HW3 a few years later, slow progress, sold that car in 2019 and got a used Model S 2018, FSD would not transfer as I bought a certified car from TESLA ~50k, came with HW3 but no software lisence , so bought the software licence again.
Just recently, I was in a car accident, rear-ended, Tesla totalled the car, and again, I could not transfer the FSD to a certified used Model S, only a new car, and now I have to buy the FSD software package yet again. I like the 2020 long-range Model S, and I'm not spending 100k on the car again. So triple screwed.
At this point, if you buy FSD, it should remain with the driver, regardless of the car you purchase; locking it to the car seems nonsensical and unfair. I think it would actually encourage people to upgrade their cars more often and stay in the TESLA ecosystem. Currently feels like getting punished.