You keep mentioning cost, and in the grand scale of "there's no such thing as a free lunch" there's a large cost but for users, they're just paying for a license from Microsoft to have copilot in their visual studio software or in M365 apps, etc.
So for helping with development, it's really not that expensive for the users. Also, "they" make lots of ridiculous claims, and i don't know who said it, but no developers in 5 years is a wild claim that no one should've thought was real.
I've only made the comment you're replying to. I'm not whoever you're thinking.