It's okay to think that someone who spent ten grand on a bicycle is foolish with their money just like I think it is foolish to keep dealing with aged parts/tech/and frame design, used stuff, or Walmart level crap. I'd personally rather have a top of the line bike than an expensive car, but I still think ten grand for a bike that isn't some custom one off is pretty silly.
I'm sure one of the reasons why manufacturers make ten thousand dollar bikes (or the top tier of their line) is so the five thousand dollar bikes look like a better deal than they really are. It's not like they are selling a ton of them, but they probably will sell a ton of $5k bikes.