Isn't it the same as asking the smokers why they smoke? Smoking
affects health, expensive isn't it? Buying expensive fast cars are
just like buying a piece of art to appreciate, feel it and own it.
I know that buying expensive sports car will cost 600K and above
but the problem is if you have the money, would you buy one to
pamper yourself? 
Honestly speaking, if you have the money, speed limits, petrol is
not a worry to you. What worrys you is that, what colour to choose
for your lamborghini. When is your new "toy car" arriving, what
beautiful number plate to get....etc..... isn't it?