"One child per woman" would quickly drop the world's population to a level which is sustainable more or less indefinitely. That population level is a lot lower

"One child per woman" would quickly drop the world's population to a level which is sustainable more or less indefinitely. That population level is a lot lower than today's - probably between 1 and two billion. The only reason humanity has got away with huge population growth so far is that we're drawing heavily on tomorrow's resources today. Those resources won't be there tomorrow. If you thought that WW2 was horrific, tomorrow's resources wars will be wholesale genocide. And what makes you think you (or your kids) will be on the winning side?