Arguably you didn't buy it. Sure you physically own the hardware but you didn't pay for it.
Depending on how you look at it the hardware was paid for by:
1. Tesla as a "marketing" expense. They expect that the $50 of hardware will make a significant number of people pay $500 for the feature. If 1/5 people upgrade that is an expected return of $100 for that $50 marketing cost.
2. The people who purchase the heated seat upgrade. It was more cost effective to install the hardware in all cars than to set up a second production line. So if 1/5 people buy this package their effective cost is $250 ($50 * 5 cars) and $250 is Tesla's buffer + profit margin. So the people who pay for this package effectively pay for the hardware in all cars.
If you enable this feature for all users both of these no longer exist. So the effective cost goes up which would likely raise the price. (Yes, I know that cost and price aren't directly related).
Depending on how you look at it the hardware was paid for by:
1. Tesla as a "marketing" expense. They expect that the $50 of hardware will make a significant number of people pay $500 for the feature. If 1/5 people upgrade that is an expected return of $100 for that $50 marketing cost.
2. The people who purchase the heated seat upgrade. It was more cost effective to install the hardware in all cars than to set up a second production line. So if 1/5 people buy this package their effective cost is $250 ($50 * 5 cars) and $250 is Tesla's buffer + profit margin. So the people who pay for this package effectively pay for the hardware in all cars.
If you enable this feature for all users both of these no longer exist. So the effective cost goes up which would likely raise the price. (Yes, I know that cost and price aren't directly related).