One of the most talked about perk of early Tesla ownership is lifetime free unlimited supercharging. Why is it so appealing? Consider that if you can afford a Tesla in early day the chance is you likely able to afford electricity to charge your car or the cost of electricity wouldn't mean much to you. But if you have ever been to Costco you will know people willingness to drive the extra distance and wait in line to save for gas. It's not so much the money but the psychology that make it so appealing.
Lifetime free unlimited supercharging is a sunk cost, since you paid for it when you purchase your Tesla. Even if you don't use superchargnig at all the cost won't be refunded therefore it's more of a use it or lose it. Since everyone purchasing a Tesla Model S/X will get free unlimited supercharging there is people who use supercharging more often indirectly pay less for their car since they benefit from supercharging. As Elon mentioned numerous times in the past, free unlimited supercharging is unsustainable and need to be eliminated. But after 2 years since that statement, it's still being used for end of quarter push.
Another is the power of zero and free, researchers had shown that consumers become irrational when it comes to free and zero. Consumers perceived something that's free being worth more than the absolute value. For the majority of the Tesla owners I doubt they spend more than a $200 in supercharging annually. Most Tesla owners likely have time of use plan or solar to offset charging cost, therefore the saving of using supercharger is even less.
Perhaps one of the biggest perceives benefit of free supercharging is the fact people think of supercharger as a gas station. Imagine a car manufacturer selling cars that come with free lifetime gasoline? This type of comparison completely missed the point of owning an EV because EV supposed to provide the convenience of being able to charge at home if you have to drive miles to charge your car for an hour that in a way defect the advantage of owning an EV.