If you willfully [if you are childless by choice] refuse to raise your own children you refuse to contribute to the survival of the society in which you live. Why at the old age you should be taken care of by the other people's children?
Do you support euthanasia?
I take care of myself and my family, and do not demand support from the government.
Do you support euthanasia?
No
Did you notice that your political philosophy matches Karl Marx?
People who don't raise children often contribute by financially assisting relatives who do have children. Also, they often take a more active role in caring for their aging parents than those who are busy raising children of their own.
Also, not all parents are good parents. And the children of bad parents are more likely mess up their children as their parents messed them up. In that case, it's better that they not become parents at all.
Raising children is not the only way to contribute to society.