If Apple's marketing were not key to its business why would they have spent over $1 billion on iPhone and iPad marketing since launching the devices (Google it)

If Apple's marketing were not key to its business why would they have spent over $1 billion on iPhone and iPad marketing since launching the devices (Google it)? Is this remarkable to you because it seems like a big number? Or is it because this is actually a lot less than what their competitors spend? Samsung alone spent a lot more than Apple did last year on marketing and advertising. What do you think of that?