....I don't understand your analogy with stocks and shares - For some people it's a very effective way of making money and the money then enables them to do whatever it is they like to do in their lives.
In my case, having a 'private plate' on my car has a definable value. I have owned the car with the plate from new and it has brought me a lot of free or heavily discounted performance modifications, given me free access to shows etc, and has even introduced me to strangers who are now friends. It has also brought pleasure to other car enthusiasts. But most of all, it adds to the feeling that my car has its own 'personality' and individuality. Finally, I can sell the plate at a profit, although I don't wish to.
If you love driving (as I do so very much) then a performance car does far more than just transport you from A to B. Every mile is a joy. 109,000 miles so far in 'RED' as she is known.
Anyway, it doesn't matter if we don't all agree about such things - Each to their own