Canada

If there is a glut of used teslas on the market, prices come down, and if you can buy a used Tesla for dirt cheap, there's less incentive to buy a new one, so it pushes those prices down as well.

Like the whole bumper sticker thing "I bought this before Elon went crazy"

How about a bumper sticker that says "this car is fully insured".

When someone buys a used Tesla, that's one less new Tesla sold = lower Tesla sales numbers, profits, and viability of dealerships. It also devalues the car.

Used car prices have been similar to new in recent years, so devaluing Teslas makes buying used a more attractive option for people who would buy one anyways.

For example, I would also rather have someone who couldn't otherwise afford an EV be buying a cheap, devalued Tesla and slapping a bunch of anti-Musk stickers on it than buying a new gas car.

Another example is I would rather have a MAGA idiot buying a used Tesla and unintentionally denying Musk another new car sale than a gas-guzzling pickup truck.