I hesitate to pay that amount of money for a Laptop. Why would I pay that amount of money for a phone which lives a much more dangerous life and only needs to render a messenger UI + take photos?

I suppose the target audience here is "tech enthusiast whales"? I kinda doubt they truly need the protections GrapheneOS provides, though.

Or rather, whatever data those protect is probably thrown out of the window anyway for other and likely not very smart reasons.