The $109k is the price of the car without FSD. Add in the $15K for FSD and you are looking at $124k new. So the difference is much greater than it would seem. Or subtract $15k from his Plaid trade-in estimate, and it gives you almost the value of my MS LR.
That infers one of two likely possibilities. FSD isn't worth Jack so even Tesla won't give you much on trade-in OR Tesla has screwed everybody on how much they upcharge for the Plaid over the LR and shows how similar they really are beyond the 3rd motor. Which goes back to a post I made a long time ago that I felt there should have been more to differentiate the Plaid from the LR.
Either of my two likely scenarios isn't a good look for Tesla. Either way, they are screwing the customer. It makes me even more thankful I didn't jump on the Plaid bandwagon. My wife would have killed me with depreciation numbers like these.