My '17 Model X 90D that's done 40,000* miles was valued at £57k about six weeks ago. It was £108k when ordered around Christmas (I blame the booze) '16. The recent valuation was during a spike in prices, where valuations were going
up. So it's about 50% after
five years.
The other points you raise are good ones. What happens if Elon goes even more crazy, screws up Tesla, and we can't get the things serviced? What if nuclear armageddon starts courtesy of Vlad & Vlod? What if solid state batteries finally reach a manufacturing breakthrough, and new cars on the market have 2x the range? There's just way too many things that are way too hard to predict, IMO. I guess look at the final balloon payments on finance plans, because those are decided by professionals rather than the ramblings of a muppet like myself
* In the grim darkness of the near future, there is only driving