I am an aerospace engineering undergrad student. I think ~1000MB of that was downloading roms in class to install and play with. Some of it is tethering. My home internet connection is only 1000Mbps/500Mbps (only service available at my rural location). Some nights when traffic is bad I will tether to my phone so that I can stay connected in WOW. Sometimes I will download files on my phone instead of on my PC so as to not take up my limited bandwidth while gaming. That's about it I think.
If VZW is monitoring usage, you're a prime candidate to hear from them.
I was thinking the same thing.