Because, I mean, we all know they are.
  1. Everybody wears them at some point
    Social equality at its finest
  2. Sometimes they have pockets and you can put snacks or your phone in the pockets
    So you can fill your hands with more snacks
  3. They're good for a lazy or sick day
    I.e. Today
  4. They look really fabulous with fuzzy multicolored socks and a t-shirt
  5. You can accidentally put them on inside out and it doesn't matter because they are just as comfy
    Once again, i.e. today