We've all heard the financial/psychological/moral arguments on why raising children makes one's life worse and less efficient. There is however, a more sinister cost to raising even one child for 20 years. That cost is worse nutritional health and thus shorter life span.
Lets briefly go over the first 3 arguments and see why the physiological one should be stressed the most.
In 2006, US Agriculture Department has found that a middle income family, with a baby, will spend $260,000 to raise the kid by the time he finishes high school. That's not taking into account economic recessions and reversals, money on college, or inflationary swings. It is very economically obvious that these types of resources can be better spent in various diversified short/long term investments. 260,000 dollars spent over 17 years can be better used to save for earlier and richer retirement, on personal professional education for better employment, or on higher rent to live in places closer to work.
Compared to real financial masochists, who spend resources to raise more than one kid, a childless person can even acquire enough extra capital to start a small business for the price of 1-3 children over 2 decades. We've heard how rearing of children hurts the poor the most but richer people also loose out on tremendous financial opportunities.
A childless person sees new options presented to him such as:
1) choice to work less
2) living in a better/pricier area
3) not be attached to one place and increase economic mobility
4) work more if desired
5) more time to be spent on talent/hobby development that might even generate wealth as time goes on.
The recent depression quickly showed how financially damaging and superfluous human breeding can be. There's been a surge of vasectomies in just the last 6 months. We can only hope vasectomy gifts become the braces equivalent for high school graduates in the future. Surely, a loving parent who wants his spawn to succeed financially, would not overlook the biggest cause of personal financial failure.
The sheer amount of extra time created through a decision to go childless is enormous. Thousands of extra hours of leisure allow a person to rest/heal more, procrastinate, think, engage in pleasurable activities, and develop the self. Person's stress levels are reduced as child related anger/worry/resentment/fear disappear. Happiness, the feeling that resistance is being continuously overcome, does not come around as often with a child. The more a person wants to be a good/prudent parent, the more the person's physiological potential is stagnated through distraction. How much satisfaction does a musician or an artist lose through not developing his/her gift fully because dirty diapers have to be changed? How much productivity does a scientist lose by being awakened at night with ghastly horrid screams?
That's not mentioning the sheer negative emotions saved if the child ever grows up to be problematic or a physiological failure. There's plenty of ways for a person to expand one's personal influence on the world. Influencing a growing organism is one of the weakest ways of doing so. If pleasure could be quantitatively measured, then the joy of seeing one's efforts successfully direct a growing organism (to one's liking) do not outweigh the pain. The sheer amount of anger, worry, stress, sadness, disappointment, resentment, shame, low self esteem cannot be made up for even if the kid grows up into a very successful adult. Positive emotions should be saved and invested during productive years so they give fruits down the line. The emotional opportunity cost of a successful child is not worth the joy of seeing the impudent elite he might become.
Moral arguments against child rearing are the weakest considering the powerful genetic commands we're under. However, if some people can be swayed by arbitrarily created external morality, then childlessness can easily aid in many moral goals. As the world prepares to accept the burden of 9 billion human beings by 2050s, anybody trying to convince people to be more environmentally friendly is wasting his/her time. The best way to reduce amount of non-biodegradable materials and various pollutions in the world, is to convince people to not create more polluters. A potential child (and potential generations of children stemming from him/her), is much more dangerous to the world's environment than a middle aged person winding down.
If it's not too outrageous for a person to reduce amount of children from 6 to 1-2 over a period of 100 years, then it's definitely not too outrageous to reduce amount of children from 1-2 to 0.
All of these reasons by themselves (with perhaps the exception of the moral ones), are enough to make any educated person recoil in horror from the idea of ruining one's life to such a degree. However, these reasons underline a deeper basic reason to not make one's life this inefficient and miserable. Undermining one's financial and psychological well being also undermines one's ability to gather better nutrition and live a longer life. The endless thousands upon thousands of dollars saved, can buy higher quality food for a childless person and increase physiological/mental functioning. Better nutrition and healthier empowered psyche from childless freedom mutually influence each other to propel a person to new heights of health. This new, stronger, more confident physiology allows one to really add years to one's life.
Perhaps if we start rephrasing the issue as a public health matter, the grave risk of having a child will become more evident. It's not just having a much better shot at riches but not crippling one's body, mental state, and life span.