Stellaris: Paradoxian Space Stategy.

[Guancyto]

Larger populations spread among a large number of planets being, by themselves, collectively dumber than a tiny population that never bothered to peek past its stratosphere is nonsensical.

That explains why, thanks to their enormous population, China was able to colonize Alpha Centauri in 1918. Later on they had to compete with India's interstellar empire (also thanks to their huge population). Certainly neither of them were outteched by a tiny island with an enormous concentration of expertise and education such as, say, Taiwan, or Great Britain, or Japan.