You aren't making any sense.
In your example I actually have a phone to use the entire time.
If the price drops a year later, that's irrelevant.
FSD on the other hand has not been delivered
It's effectively PREORDER
So yes, if the price dropped before they ever actually delivered the product, I'd absolutely expect to get some of my pre-payment back. As should anybody. As does anybody with literally any other product from any other company.
As noted elsewhere that would require a flux capacity, and the Model 3 battery can't output the 1.21 GW needed.
Now, if I could refuse delivery of my preorder of FSD that still has not been delivered and rebuy at the new lower price, like you can for every other preorder in the world, that'd be great.
Tesla doesn't seem willing to let anyone to that though.
Does the contract you signed, say anything about being entitled to price reductions?