Being anti-abortion because “people need to learn a lesson” is absolute bullshit. You can’t ‘punish’ someone with the responsibility of being in total care of the well-being of another human being.
Obviously, someone never using protection despite not wanting a child is very irresponsible, but do you really want that same irresponsible person to carry a child for nine months, or even raise a human to become a functioning member of society?
“I don’t want a child” is a perfectly fine excuse to have an abortion. You can’t force someone to put such a huge physical and emotional strain on their life, sometimes just because the contraception was ineffective.
Pregnancy and parenthood completely alter people’s lives. If someone doesn’t want one or both of these things, let them end it.