I can't tell you about Tesla, but BMW for example did shoot themselves right in the foot by announcing literally at the launch of the iX that they are going to bring a new model with updated 800V architecture within couple years. So........why would you buy that first one, knowing that a much improved model is literally right around the corner. Consequently prices of the iX cratered, and you could have it on a lease for the same cost as a VW golf, despite being (at least in theory) 3x more expensive. The first gen cars are now so laughably cheap it's actually stupid to not buy one because they are still perfectly good very capable vehicles - but yeah, why would it keep value if it was immediately replaced by a much better model. With EVs we're in the GPU area where each model immediately displaces the last generation and within few years your top of the line flagship card is worth close to nothing.

https://en.wikipedia.org/wiki/Osborne_effect