What are the cons of NOT having kids?

The cons are mostly demographic and societal. With all things sexual reproduction is the ultimate goal as far as nature is concerned. Your instincts turn to species survival and individual survival is forfeit. The obvious personal effect of not having children would be not having the support of children in your old age. That assumes of course that your children actually help you in your old age. If you give rise to sociopaths, you can forget that. They would probably be a threat to you instead.