It's so personal to the individual.
For example, eldest DS has additional needs, and he was all we knew. Very happily raised DS, although some very challenging times within that, which were not so happy, but essentially manageable.
I would have been happy as a parent.
We then had DTwins. I suspect one has the same condition as DS but too young to be diagnosed. Other twin, completely NT. She is an absolute dream of a child. And I feel so lucky to have experienced what I presume most do for all their children, it's easier and more enjoyable by a country mile.
Had I never had her, I would have been entirely unaware this is what raising an NT child is like, and would not have missed what I didn't know. I would have been happy with my ND children.
I think there are always anxieties about becoming a parent. It is, the great unknown. For most, it's a happy decision. For others, not so. And yes, it is a gamble not knowing the cards you will be dealt. I would say 95% of parents are happy now they are parents.