Talk to your friends, they might verbally say 'money', but then you see them go on trips and buy food at restaurants. Its much easier socially to say 'money', than 'I don't like/want kids'.
The only reason I have a ton of kids, is because I am planning on setting them up for political purposes as I play Dynasty. Its selfish, and I hope to make lots of money and power from them.
No one else has this mentality. The better question is: "Why does someone want kids?"
Given most people are hedonists(assumed). Would a hedonist want kids? Maybe. They are cute which is dopamine inducing. But less fancy food and lots of crying pains.