Why are Chromebooks so expensive?

Hey guys I'm in HS and every so often in school we will use Chromebooks for assignments. They do the job just fine even if they are a bit slow, but one day I was on Youtube when I discovered that some Chrombooks go for 500, 600 sometimes even $700. I just don't quite understand what is so amazing about Chromebooks compared to other laptops that would justify that price.

If you want cheapness/value you can find old Dell Optiplex's on sale for ~125$ and many 200$ Windows laptops that can do many more things then Chromebooks

If you want power, it's a laptop. And to my understanding everything is done in-browser on ChromeOS anyway so power is a minimal concern at best. You can also find some very nice laptops that can do anything minus Photoshop/Premier for under $500

If you want sleekness, 2015 Macbook's are going for around $400, still pretty pricey but not absurd.

If you own one of these high end Chromebooks, please explain what the deal is with them. Just to be clear if you want to buy high end Chromebooks, more power to you. I honestly don't care what kind of computer you use if that's what fits your needs. But seriously. Why are they so expensive?

EDIT: Thanks for the responses, It seems the main reason for expensive Chromebooks is for people to have high build quality and no extra stuff they don't need. Thanks for clearing this up.