So to preface this, my spouse and I are trying for our first kid so I'm not a parent yet, but I've been reading a lot and talking to friends who are parents.
> If the life they are coming to is already bad, financially, legged behind from others in many ways, or any other, that's selfish. Forcing someone to terrible start without their consent.
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> Parent should first make sure they are good to bring someone else and not to give a disadvantage start, playing gamble with life who did not ask.
Literally every aspect of raising a kid is a gamble, but there are degrees to these things. What counts as a "disadvantage" isn't always clear, let alone the degree to which it is actually harmful. Making a few mistakes or not doing things perfectly is probably fine. There is a huge problem with pregnancy and parenthood where controlled studies can't be done for ethical reasons, the number of confounding variables is about as extreme as it can get, and the outcomes you're measuring often aren't even well defined (what does it mean to have succeeded as a parent? What does it mean for someone to have a happy life?).
It's important to try to make your kids have a happy life, but there's a lot of disagreement on how exactly to do that. One factor that seems to have a huge effect is having parents who express their love for their kids and spend time with them. It's important for parents to take care of themselves and their relationship with their partner. One part of that is not burning yourself out trying to hyper-optimize things.