Howdy. I like how you hold no punches on your blog but normally you are good about backing them up with data. I hope to meet you some day.
The precise quote from my client that uses TeraData is "I.T. charges me $1M for each TB I use". I know that's very different from what it costs the business but it is still a very damning number. That's basically a fully loaded cost to an end business unit.
If costs are CLOSE to being that high, then data volumes are a very poor metric for cost allocation. 2+ people per terabyte are being counted in, so either there are a huge number of tables, or they're including BI developers, or something.
E.g., doubling the size of every table, if nothing else changed, might only take those costs up 10%, give or take a factor of 2.