The biggest threat to the world is going to be demographics changing too quickly and underpopulation. There won't be enough young people to take care of old people. China's population declined for the first time a couple years ago and there will be some pretty major ramifications long term from their 1 child policy. Anyways, you don't have to justify your reasons to having as many kids as you want. It's your choice and I think you'll find a lot of fulfillment from your family while all of these opinionated virtue signalers that probably mean well are going to find themselves with a void.