Because if you ban abortion for one person, then you are banning it from everyone. It's like saying a man controls what happens in a woman's body. No. They don't.
A woman should get to decide what happens with her body, her uterus..her offspring. If she's not ready to have one, then let the woman make the choice. Some people can be against it and decide for THEMSELVES that they don't want to abort, but you cannot take that choice or decision from somebody simply because you disagree with it. It's like the trans movement.
If I want to call you a man when you transition into a female, let me do as I please. I should not have to change my beliefs on biology because you want to be something else one morning. No, every chromosome in your body is male. You are biologically a man. People should not have the right to press their opinion onto me, just like they shouldn't have the right to dictate what a female does with HER body. I should not be penalized for my beliefs differing from yours, just as a woman shouldn't have her choice made for her when it comes to abortion