A large portion of B&W speakers' price charges customers for fit, finish, and exclusivity. Do they sound 20x better than good $1000 speakers? short answer - hell no. As AcuDefTechGuy mentioned, there is a definite case of diminishing returns here.
There are many more expensive speakers out there a plenty. These 20k speakers aren't even the most expensive B&W makes.
But, true high-end sound isn't cheap. The issue is that the difference in quality from a 3k system to a 300k system will never be 100x better sound quality.