collapse of the old society

I've read The Selfish Gene and also studied Biology, earning a BS in the process. One thing you fail to consider is your genes are diluted with each generation. Your children will have 50% of your genes, your grandchildren 25%, and their children will each have 12.5% of your precious genes. And lest you think your genes are somehow unique and valuable, most likely 100% of them already exist in other people.

You also fail to mention that Dawkins, rightfully concerned about those using his work to justify selfishness, explicitly discusses how, now that we know of these selfish-replicators, we can cultivate pure altruism - going against our biological programming and doing the right thing. That's what people who choose not to have children are doing - they are acting in the best interests of humanity.