Its interesting I had a friend who got pregnant at University. I thought it would be ruinous to their career but maybe its a better solution. When she was 40 her child was already an adult and she could fully concentrate on working.
I think if I had known how young late 30s and 40s actually is it may have resonated. Like, I still do all of the hobbies and activities I did in my 20s and am arguably in the best shape of my life, pandemic bod not withstanding. I think I truly felt my youth was fleeting and I wanted to be able to "enjoy it".
The reality is I squandered it in some ways and I feel a bit of sadness that my children will have a dad in his 60s by the time they are out of the house. Should have given that youthful energy to them with something to spare as adults. In reality I probably won't have much left when they become adults.
Such is life!
EDIT: Someone down thread makes another point that applied to us. By the time we were "ready", we found we had "unexplained infertility". Science helped us out but it wasn't fun, it was stressful, and pushed our parenthood even later than planned.