I guess it becomes different if instead of hiring more people to do more - all investment goes into more AI credits.

Then again, as long as there is more demand and there's a limited supply of compute you can still continue to hire people as well. If we assume that the market has infinite demand for whatever AI + humans can produce together both will have jobs.

If demand is limited and compute is plentiful it should make sense for a company to try to have AI do as much of the work as possible.