The day my oldest son (he’s 16) was born I was holding him and my mom said “enjoy every minute because you’ll blink and it will be over”. I got two years left and he’s off to college. Just two years, it feels like I’m getting fired. She was right, as mothers usually are.
This sounds very judgmental. Don't assume there's a single way to live a happy life. People with kids aren't immune to depression or lack of purpose.