Simulation is the answer. You just need a model that's decent at economics to independently judge the outcome, unless the model itself is smart enough. Then it becomes a self-reinforcing training environment.

Now, depending on how good your simulation is, it may or may not be useful, but still, that's how you do it. Something like https://en.wikipedia.org/wiki/MuZero

Electric dreams. Simulation of what?

  doable but not easy, for business ideas

That requires a lot of human psychology and advanced hard economic theory (not the fluffy academic kind). With human controlled monetary supply and most high-level business requiring illegal and immoral exploitation of law and humans in general, it's not a path machines can realistically go down or even want machines treading down.

Think scams and pure resource extraction. They won't consider many impacts outside of bottom line.

Simulated environment suggests the possibility of alignment during training but real time, real world, data streams are better.

But the larger point stands: you don't need an environment to explore the abstraction landscape prescribed by systems thinking. You only need the environment at the human interface.