Yes, there are billions and billions of human beings on earth right now, but we still only inhabit a small percentage of the earth. Some say that about 3% of the earth’s surface has been urbanized for living. We may want to explore floating cities.
If you gave every man, woman, and child on earth a 1/10 acre allotment (about 20 yds by 20 yds, so a family of 5 gets a spacious half acre for a nice modern western residence and good yard for mowing), you would be able to place the Earth's entire population into...
ARGENTINA.
Now go look at a globe. Now look at the land area that is NOT Argentina.
We are a long, long away away from overpopulation.
(SF has a population density of 17,246 people per sq mi... which gives each person around 1/30 of an acre each... only 1/3 of what I alloted above. If we lived with the population density of SF, we could fit the entire earth's population into Texas.)