Offline
I'm not sure why other than you could. Unless you could figure out the payload you'd likely wind up with a bell pepper and roll of TP.
Mischief? Mayhem? It's one thing to fly your own drone for some malevolent purpose - but if you could hack one, it might make it easier to get away with? I'm not sure.
Or perhaps with Amazon you could have some kind of Robin Hood agenda - if you could take over the drone and eliminate Amazon's ability to track it, you could deliver the items to underprivileged neighborhoods.