Musk is brilliant.

Because the supply of BTC is limited, the market for it can be cornered. No one cares what BTC are worth, because you can always buy as much as you need and transfer it immediately without risk. Meanwhile, Tesla simply creates a black hole, driving up the price.

Of course, anyone who uses BTC to buy a Tesla needs to pay taxes on the gain in the BTC. So you will probably want to buy BTC at current value to transfer to buy the car. So it's just a gimmick to you, but part of Musk's market-cornering plan for him.