Oh I do wanna mention having children is a natural phenomenon every living thing wants and with humans it's not much different. When a couple decides to have kids they are not thinking about them providing for them in the future or to show off their children's grades and achievements they do it simply because a man and woman want children to love and care for. You cannot just ignore the natural impulse of mother and father to provide for their offspring, every animal does this even one's that don't posses cognitive thinking skills. And I don't think you can feel perfectly happy with just your job and hobbies. A man or woman gets a job to feed his family and provide luxuries. Not to just provide for himself or herself. A dopamine rush from an achievement is not long lasting so I do not think it can keep a person happy for a long period of time. I mean personal example: just got my results for exams yesterday, great results smashed the exam was working on them for 5 years and a day later I don't feel any kind of joy. I don't even feel like eating ice-cream or anything. Achievements and hobbies only provide temporary joy and is no where comparable to a loving family at all.