If you see the world that simplistic, maybe you should have refrained from procreating.
Birth control can fail. Pills can be forgotten or interfere with other medications, IUDs can fall out unnoticed, condoms can break or slip off, etc.
If you have sex often enough, the chances of having birth control fail at some point creep up to 100%, and if you’re “lucky” that results in a pregnancy, and if the mother either has no access to abortions, or simply doesn’t want one, you have a child.
Unplanned doesn’t mean unwanted or unloved. Many people in principle would like a child but don’t know if now is the right time and this person is the right partner, but if random chance over, they’ll take that hint and become parents.
And Hitler planned to conquer the world.
There’s a good chance, you simply cannot retire in 30 years. Or at least not fully. State funded pensions are struggling worldwide. If less new tax payers are coming in, whose taxes pay your pension?