It’s the same reason you buy a Rolex. A quartz watch can keep time better. It’s about signaling status and it’s a bonus that it’s fun to ride.
Which is amusing because the only thing you can know about someone with a car like this is they have $200,000 less in the bank than before they bought it.
I remember reading that more than half of all Ferrari sales are financed and that most Ferrari owners have a net worth of less than a million dollars.
It seems that people are willing to strain their finances to signal status.
The tiny amount of gem decorated watches they sell are all sold with diamonds certified by the Kimberley Process, which isn't perfect, but is literally the UN standard.
I would spend my money on something else though, Volkwagens aren't that great /s