you could try raising the level of education. breeding a whole bunch of people and hoping some of them teach themselves to be useful isn't really a great way of maximizing intellectual output
certainly education is vital to a modern economy (and society), but I suspect that you hit diminishing returns at our current levels - not many more can really benefit from e.g. post graduate studies. Sending ~50% of school leavers to uni in the UK has arguably been counter productive, as instead of a path for the talented to rise, uni has become more a rubber stamp for entry into the middle class and course content has become diluted (and then loans on top to pay for it all)
> but I suspect that you hit diminishing returns at our current levels
I think there are plenty of uses for another million bioengineering grads. Combine the grads with R&D funding and we’d see a regular cadence of medical miracles.
Similar for materials scientists, robotics engineers, etc.
Also on a low tech side, a million more teachers, teaching much smaller classrooms, might pay for itself many times over.