Even as a personal belief it can be problematic when it causes harm to children you have while your own life circumstances don't really make that a good idea (e.g. being gravely ill and dying soon after the birth, leaving the child a predictable orphan; having genetic diseases that will kill any children you have after significant suffering with no chance of a cure;...). There are always at least two people to consider in any decision not to abort, even if one is only a future potential person (but unlike the decision to abort, where that person does not exist in that future, when they are born they actually can suffer).

It isn't really shocking if you look at it objectively and see from their perspective for a moment.

A genuine pro-lifer, by definition, believes that abortion is morally equivalent to murdering a newborn, because the unborn is equivalent to a baby, to them.

So imagine how such a person would read what you just said:

It is perfectly fine being against murder for personal beliefs, but to be against giving others the choice to murder is shocking.

It's understandable that the above sentiment would come off like the words of a madman.

Because there is truly no 'debate' to actually be had about whether or not one believes the unborn 'count' as babies, it's completely futile to argue with pro-lifers on that axis.

Nor should one be surprised that they are 'anti choice for others' when itI comes to this, as I am sure you are against others having the choice to murder at will, regardless of whether you wish to murder anyone.

It's like saying that it's shocking that a hypothetical group of people who believe theft is the worst possible crime you can commit, believe in capital punishment for thieves. Sure, it sounds bizarre to everyone else, but it shouldn't be surprising at all that they feel that way, given that they believe.