Geothermal, wind, solar, heat, tide, etc. currently amount to a staggering 1.5% of the total primary energy supply of the world. Coil is at 28%, oil is at 31%, natural gas at 22% (and climbing), nuclear at 5%, etc. CO2 emissions continue climbing year after year, and we should have started going down more than twenty years ago.
Our agricultural system is completely dependent on fossil fuels (oil). Because of that it is mostly unsustainable, and also because it tends to destroy fertile lands (topsoil loss is kind of a big issue).
You are kind of right that the current system can support a lot of people. Unfortunately, almost none of it is sustainable. So making more people is really not a good idea at the moment, because the situation will change drastically over the next 80 years.
https://www.scientificamerican.com/article/u-s-reports-a-maj...