Google owns the .dev TLD, and they bought it for entirely internal use. People got upset about this (any company owning a TLD for internal use only is pretty weird, and especially one as generic as ".dev") so they started to offer it to the public.
The bigger issue is that a lot of people use .dev for internal/development uses, and it should therefore never been made into a "real" TLD in the first place. It's like deciding to sell "example.com" to someone.