Apple is on both the list of licensors and the list of licensees. In other words, they own some of the patents in the pool, and they pay to use those patents in the pool that they do not own. In order for Apple to make a profit on patent licenses, they would have to either own a majority of patents in the pool (if all of the patents are of equal weight) or those patents that they do own would have to have greater weight than all of the patents that are owned by others.

It's hard to say whether Apple actually gains anything. For all we know, they might be happy to break even.