First of all, speed is hardly a feature when compared with laptops on the same price range.
Specially when taking into consideration the VMs being executed, namely browser instances, gVisor and the Crostini hypervisor.
Then just like on Android devices, Chromebooks have a limited duration of updates, namely 6 years since device market release.
Hardware quality is debatable when I need to pay MacBook class prices for getting such quality.
It’s true that after some number of years, you switch the hardware to a different OS, including a 3rd party supported ChromeOS system or a variety of Linux distributions.
I’m not saying it’s for everyone, but I will say that it’s at least in the same class of consideration as “you could buy an old Thinkpad, and replace at least the hard drive, keyboard, display, and battery to get something similarly usable”.
Chromebook's security story is far ahead. You can do your own research and you'll find ample links proving the same.
My Windows and Linux laptops are kept up to date since ever, with hardware encryption turned on.
This discussion is about the permissions that applications get. Desktop Linuxes don't have such an permission system in place - "just run as root" with ultimate trust in the application is quite common. Sandboxing isn't a thing either.
Amount of Chromebooks on sale across European electronic consumer stores, less than 1%.
The 1% is left for when they occasionally pop up under "deal of the day", when the shop decides to test waters and is more than happy when it finally goes away after a couple of weeks on display.
GNU/Linux security is better than ChromeOS because the updates are guaranteed for longer than six years, if one buys a laptop from someone like System76, or plenty of small Linux shops, it can be properly configured with encryption, LinuxSE, Flatpak/Snap/whatever.
Windows is a proper OS and its cloud offerings are not new.
Security must be the default. Automatic updates, sane default configuration. And a user interface that supports security.