Folks, I assure you if the greatest minds of our generation were working on the problem of how to live sustainably on a planet with 8B+ people, we'd get there. Our society is not organized to solve problems like that; instead, the brightest minds of our generation are employed to "make the line go up" and play math games with stock trading.
The problem is not "too many people." You got lied to by capitalists who sincerely believe that there is no other option but capitalism. Period.