Personally, I've never understood the selfishness argument, especially by parents, as 1) Isn't it more selfish to create a literal new entity of life just for your own whims? and 2) What is wrong with selfishness, especially in light of their own selfishness in 1?

This is not even to mention that many parents simply do not care for their children well, as parental child abuse cases as well as the number of potential adoptees in the world is non-trivial. Now that is truly a cruelly selfish act more than any amount of not having kids can be, to bring a conscious entity into the world and then to let it suffer.