If you have the money to buy a supercar then why don't you? We spend money everyday on wasteful things. I think that it would be neat to own something that is considered luxury, but I don't have the money. I won't judge someone on what they can afford as long as they aren't trying to be rude or better then myself. Also I think it's better then supporting drugs, and violence.
If your vehicle gets you from point A to point B safely and securely, then it is money well spent. If the supercar drives itself, does your laundry, picks up the kids, and pays your bills, then you could considered $150,000 'worth the money'. It seems that people might have other things to spend their limited funding on though.
No, I do not think that an expensive car is worth the money. I don't see what most other people see in having the biggest best car and I could really care less about what I drive, as long as it runs. They all end up breaking or needing work done on them in the end no matter how much money you pay.
A super car is not an investment. Vehicles should be based on safety, economy and convenience. A supercar provides none of those items, and costs an exhorbitant amount of money. Cars quickly depreciate, and there is no way to make money on the sale of a used one. A super car is an indulgence only.