The assumption here is that an AI with IQ 100 could do anything a human with an IQ of 100 could do, only cheaper. But that's just averages. Really it would do half the things better and half worse, and then people have jobs doing the things that it does worse.
That would continue until it doesn't do anything worse, which may or may not ever happen, but if it did and we're all still alive then the result would be post-scarcity and nobody would need a job.
That would continue until it doesn't do anything worse, which may or may not ever happen, but if it did and we're all still alive then the result would be post-scarcity and nobody would need a job.