Just question them and they'll look stupid. I had someone pull that on me one time I brought up "movies are fake" and it led to a responses of "But it's different". I asked "How so?" and they stood there puzzled, confused, and stupid.
It's just something people say to be assholes. They don't actually hold any contempt towards wrestling, they just want to be cool and call it fake. Inquire about their reasoning and they fall apart.