What if having a big family brings me joy? If welfare and basic income provide the support I need to have a huge family without being productive, why would I choose to live a life that is inconsistent with my life's motivations? Why work for a living when I can do what I want, and be just as comfortable? I don't need a Tesla, so I'll leave the working for the chumps.

Congratulations, you get to be productive by raising society's next generation.

Sincerely. Many people don't desire large families, if any, or are physically incapable of reproduction. So why pressure them to when others are perfectly willing to pick up the slack?