We had one by choice. We thought "let's have one, then see how it goes for another". Every time a milestone was passed I breathed a 'thank fuck for that' sigh of relief - walking, talking, out of nappies, out of the pushchair, end of tantrums. And he very rarely tantrummed.
He's now 8.5yo and has not once asked for a sibling. We have his friends over, he's invited to theirs, we meet in groups in parks, on the beach, on holiday. We go camping with the dog, bike rides, play boardgames, do experiments, walks in the woods, hike mountains, visit castles museums and caves, have cool picnics...either us three or with other families.
DS is kind and generous, doesn't fight, doesn't get angry, shares, is great with kids of any age, chatty to hates football, not creative. Basically he's a normal child who just happens to not have a sibling.
DH is one of 6, doesnt speak to one, strained relationship with two others. I have one older sibling, we live opposite sides of the world, don't get on at all although we can be civil. Hated each other until late-20s. Old age care will fall on neither of our shoulders as neither of us are in the same country as our parents. I can get there quicker.
There are nothing but stereotypes and anecdata surrounding: no kids, one kid, three kids, 4+ kids.
paddingtonthebear it is fine to question why someone has one child absolutely not! I've told two people to MYOB when I've been asked, total strangers, sticking their nose in my uterus and my sex life! (*I may have misquoted, am on my phone and it's quite a scroll up!).