Humans could go interplanetary, create generation ships, or even develop FTL and go interstellar if they would devote as much time and energy into these things as they currently do going to war with each other or hoarding resources.

The nearby asteroids are awash with mineral riches, the Moon has water, and it may be possible to terraform Mars and Venus. The outer worlds have tons of moons that may be able to support robotic manufacturing for materials that can be used for space stations.

The construction of even ONE space elevator would catapult the industry to new levels of experimental learning.

So, ultimately, it's not about population control, or anything other than just discarding outdated ways of being 'ruled.' Get rid of archaic constructs like monarchies, dictatorships, republics and democracies and get serious about uniting humanity in a worthwhile endeavor.