The choice to have kids in the first place is a purely individual choice. For some, it may be incredibly important. For others, I think it's perfectly acceptable to opt out of the whole thing.

Once you've had the kids, however, I'd suggest that most startups (perhaps not absolutely all) are objectively less important than making sure your kids grow up to be decent, empathetic, constructive members of society – for whatever definition of society you choose. It may be tough for your kid to grow up to change everyone's world, but it's really easy to let one grow up to destroy someone's world, and preventing that is the job you took on when you decided to take the step of having a child that may one day interact with mine.