J.k. Rowling said this quote
“ SO WHAT Harry shouted. Don't you understand? If Snape gets hold of the Stone, Voldemort's coming back! Haven't you heard what it was like when he was trying to take over? There won't be any Hogwarts to get expelled from! He'll flatten it, or turn it into a school for the Dark Arts! Losing points doesn't matter anymore, can't you see? Do you think he'll leave you and your families alone if Gryffindor wins the house cup? If I get caught before I can get to the Stone, well, I'll have to go back to the Dursleys and wait for Voldemort to find me there, it's only dying a bit later than I would have, because I'm never going over to the Dark Side! ”