There is a reason they cost so much.
As for why someone would spend so much, you live with this animal 24/7 for hopefully a decade of your life. That personally makes the price worth it when you talk about predictable temperament, size, and personality characteristics.
I also think all dogs are awesome and rescuing a dog is a very cool thing to do. But I wouldn’t trade our dog for anything and she was 100% worth it.
Disclaimer: My wife and I have collectively owned 9 dogs of 6 different breeds.