For a non-tech case of this, my wife worked at a place that fired like 80% of their writers in anticipation of huge speed-ups they expected from LLMs, a couple years ago.

They had to hire a bunch of them back less than two months later. The speed-ups were approximately nil and making the editors edit AI slop all day long had them all close to quitting.

They didn't even wait to see if there were any actual benefits, they just blindly fired a bunch of people based on marketing lies. I can only assume they're the same sorts who fall for Nigerian Prince scams.