Maybe the joy of driving, the speed, the looks. Maybe watching your money go out the window as you add parts, then remember they only bring down the resale value.
Heh, I guess it's no different than being excited about video games. I guess, if you like driving and like dreaming about cars you'll likely never own, you'll enjoy it. If you drive an automatic (aka don't experience the fun of driving) and you'd rather spend $300 on a Xbox instead of some Skunk2 Coil-overs, you probably won't see the fun in it.
And then there's the fact that some car shows have bikini and booty shaking contests
