There's a great scene from a Michael Winterbottom movie called Jude where --spoiler-- a child asks his parents why they had him if they could not afford him and his siblings. The child doesn't like the answer and ends up hanging himself and his siblings.
I don't know if there is a solution. People want to have kids, even if they can't - in my opinion - afford them. Some religions encourage having lots of children - it's a big thing in the catholic community, at least where I grew up.
Anecdote: My cousin is married to a catholic latina, he's already struggling to make ends meet taking care of the one kid they have. He lives with her grandparents and cousins in a tiny apartment in a low income neighborhood. There is no way I could talk him out of having another child, even though I know it's fiscally irresponsible in my opinion.
I think it's a conversation worth having but I just don't know how it can go anywhere, and I have struggled to come up with an answer that isn't just me being upset with the parents.