Know how many kids you can handle / afford. Is one enough? Two? You can have a family, pass on your traditions / genes without creating too large a financial / time burden.
If you're successful enough to work at / start a startup, you can probably afford a nanny. If one of you can work from home, you can have a nanny w/o having to worry about leaving your kids with a (near) stranger. Even for people with middling careers, two incomes + nanny expenses is usually better than one income, one full time parent.
My wife and I both work, a lot. We have demanding careers. We've had the exact number of children that we're confident we can afford long term without compromises. We have a nanny. I work from home to supervise the nanny and make sure our children are ok.
We have an awesome relationship with our children and are involved in their lives as much as anyone else. There is a bit of juggling e.g., taking turns attending school meetings but that's not really a big deal.
Both of our incomes have increased since we started having children. Neither of us saw a dip in income. My wife did not have to choose family vs career.
If you're thinking there's no way you could do / afford this then seriously consider foregoing the "let's get rich" startup or children. The idea that everyone thinks they can have everything is absurd. That's harsh reality but reality nevertheless.
Unless you're wealthy or live off of the government, children and startups are a luxury. Stop whining about what you don't get. We all have choices. No one has to have kids or work at a startup.