Having grown up as a military brat I know about poor and I know that this kind of self-serving look-down-your-nose "advice" is just rationalization for living well in a society that enables sociopathy
I'm sorry you had to go through that as a kid. My beliefs on this subject are rooted in an empathy and caring for kids who could have had better childhoods if their parents had their shit together a little more.
Having kids when not entirely 100% secure in your future is not necessarily a bad thing, as long as the parents make sure things go okay for the family. But that's hardly the case most of the time, and people over-extend way more than they can conceivably manage/sacrifice-to-handle. That's where family planning should help (by sharing knowledge), not just giving out free birth-control.
People need to be damn sure that they can provide for the kids, or that they will give 110% in order to make it so. But, welfare is sadly pretty-much at a point where it's just paying people en-masse to have children rather than helping people that got into bad situations. That's not moving society forward, or helping the needy; that's creating/breeding generation upon generation of a dependent under-class that will just vote to reinforce said government handouts.