And yet it's perfectly true. Sorry you feel condescended to. People who say this are relating their own experience of being parents and how they couldn't anticipate how much it would change them.
It can be true that parents can feel that way, yet it is also true that not all parents feel that way, especially among younger parents, else abusive or neglectful parents would not be a thing.
Having a child may be meaningful to a parent, but it is not at all true that applies to all childless people. Continuing to insist on that anyway is just showing sheer disregard for the well-being of a child born to parents who turn out to not actually be all that concerned about parenthood.
