It's the same reason guys buy a F-350 Super Duty Diesel Super Cab to drive 20min across town to work.
I was just looking at a couple of those! Add the power chip and the oversize induction system to the Powerstroke Diesel and things get interesting! I don't drive even 3 miles to work and drag a heavily loaded trailer but once a year. I can't speak for the other "bad guys" but I'm thinking I want one simply because I REALLY LIKE IT A LOTT, kinda the same way I choose firearms. I wouldn't go with the duelly package though --- even in 4WD, not too good in deep snow, IMHO.
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BTW, how is your uncle's buffalo ranching going?