Because I have too much stuff

Barry: My place is three-stories. The stairs kill me.
Me: Yeah, my place is only two stories, and sometimes the stairs kill me.
Barry: You live by yourself?
Me: Yes.
Barry: In two stories?
Me:And two bedrooms. And two and a half bathrooms. And a two-car garage.
Barry: Why do you need all that space for just yourself?
Me: Because I’m a grown-up.
Barry: Good answer.