YouTube may be a business but, if you take away online advertising there, it wouldn't be a successful one. In fact, one of the first things people bring up when discussing YouTube from that standpoint is how much money it loses. If Google wasn't one of the richest corporations in the world, YouTube would have been killed off a long time ago. I'm frankly not even sure that the advertisements are enough to sustain it even now, would have to check the recent data.