I can back this up, I'm just one guy who doesn't do any BTing and I often have to pay as much for bandwidth over my cap during the big Steam sales than I do for the games themselves. Obviously some of the folks here haven't downloaded any recent games, Borderlands I? 37Gb for the game and DLC, Borderlands II? 42GB for the same. Heck even a game with very little DLC, as the Burnout Paradise i got with the recent Humble Bundle? Over 4Gb, now figure in the other 8 games that came with the bundle and you are easily looking at 25Gb+ right there and that is just for a single bundle!
Trust me friend that 150Gb might seem like a not but its not and just be glad you are getting even that, the local ISPs here have plans that are 36Gb,60Gb and the top is 76Gb! These ISPs act like its still 1998 and all folks are doing is checking their email, when IRL everything has gotten bigger EXCEPT their caps.