No wealthy person is going to save money by relocating from California to avoid a $30-40k tax bill on an exotic car. Wealthy people have a beach house in California because they like California.

The people who relocate to avoid taxes are upper-middle class people who are overextended on their finances.

Well they go through the trouble to form an LLC in Montana to own the car, to (illegally) avoid that tax bill. So clearly the tax isn't something they are just happy to pay. The LLC probably owns the beach house too, for some other tax dodge.