Isn't this the same in any field? It's likely been covered before, but at the very utmost area of performance, you see diminishing returns.
A top of the line PC is around $3000. You can build a system with ~85% of the performance for $1300.
A top of the line car is $2,000,000 (as was stated earlier). It is not going to be another world of performance than a $250,000 car if you look at track times, which is not going to be in another world of performance than a Corvette or a Nissan GT-R. For people who care about going fast -- a ~$60-80k performance car is going to be more than fast enough. For people who are true speed enthusiasts, and can afford it, then you're looking at something much more expensive.
Everything is the same -- from pianos to computers to supercars to the materials you build your house out of. You're going to pay for those last few deviations from the norm for performance.