What is odd is that FSD does not seem to be adding nearly the amount to the cars in the used market that it should. FSD should not depreciate like the mechanical parts of the car. The same people willing to pay $12K to add FSD to their new car should also be willing to pay that to add it to a used car (as they can do if it doesn't come with FSD.) Or at the very least, pay what fraction of the FSD price matches the discount on the car even though it doesn't wear out like the car does.
But from what I have heard, they don't. FSD does transfer in private sales. If you sell back to Tesla (trade-in) they give you nothing for the FSD and just wipe it from the car, so don't trade-in if you have FSD. You'll get some bump but a small one, it seems.
If this were not true, you could have less fear of buying it, knowing you would get the money back on resale.
In general, the best plan is not to buy FSD and just put the same money into TSLA. If Tesla delivers on FSD, TSLA stock will go up *much* more than the cost of FSD will go up. If Tesla does not deliver, the stock may go down a bit, but not to zero, which is what your FSD is worth if they don't deliver. Well, not quite zero, you will get smart summon.