It's a dumb meme that ignores that Kevin is also only 7 years old *and* that he attempted to avoid the entire confrontation multiple times by trying to convince both Harry and Marv that he was not, in fact, home alone. On the first night, he runs around, turning on the lights, to convince them that someone is still in the house. On the second night, he stages a party to make them think people are home. It's only when they come back a third time that he resorts to physical confrontation, fighting back.

Also, you know... it's a movie.