I'll try and make it simple, although it's already evident, so...
If you're in favour of cutting a social security benefit or denying it on undetailed cost grounds, then you're a hypocrite if you don't accept the cut/denial applies to everyone in a category (in this case, people with children). There is no difference between taking support if you have one child, or taking support if you have 3 children.
From your position on the scale, you argue that you "only" had one child you expected taxpayers to support, so that's okay. But from my position (no kids, worked so far for 36 years) you used my taxes to support a child you chose to have, exactly the same as someone who may have 3 or 4 kids. In the language some people like to use, you were quick enough with your hand out for a handout when you needed it. But you want to remove that tight from other people. Hence - hypocrite.
Btw - there are around 24,000 families with six or more children, and "a handful" with more than 10. So stop with the tabloid headline nonsense. Unless, of course, you really want people to think you're stupid enough to believe it.