Jokes aside, a true agi would displace literally every job over time. Once agi + robot exists, what is the purpose for people anymore. That's the doom, mass societal existentialism. Probably worse than if aliens landed on earth.
It does, almost, exactly what the movies claimed it could do.
The, super-fun, people working in national defense watched Terminator and instead of taking the story as a cautionary tale, used the movies as a blueprint.
This outcome in a microcosm is bad enough, but take in the direction AI is going and humanity has some real bad times ahead.
Even without killer autonomous robots.