I’ve read that the energy industry grew after standard oil was broken up and the standard oil shareholders did better as they owned parts of all the new companies.
How could that be validated? More energy was going to be used no matter what due to increasing population and technological advances leading to increased uses of motors, etc and the whole industrial revolution.
There was a lot of activity after they were broken up. Not conclusive, but in the short term it led to a lot of economic activity. My guess is that monopolies lead to stagnation in the medium to long term.