Some kids who are the only child in the family wish they had siblings, while some kids with siblings wish they were the only child, amirite?

This is hardly an opinion. Of course some do.

The oldest child in a family (if not twins or more) experiences both.

I like having a sister who lives on another continent. Living with her takes away too much of my privacy and creates a lot of tension and conflict between us, but I don't wish to be an only child because we often help each other out.