My wife drove a Toyota Sequoia for 12 years before we bought her current SUV. The Sequoia was a solid, reliable car that got the job done. She did not wear it out in those 12 years--not even close--but at some point it just got a bit dated and she wanted a newer car with more modern features. We were considering a new Sequoia to replace it, but then she drove a few German SUVs for grins, at which point, all bets were off.
She ended up picking a Mercedes SUV over a new Toyota even though it was more expensive and (we assumed) would be less reliable than a Toyota. The primary reason for her choice was that it provided a better driving experience in almost every way that was important to her. I would have preferred she got a new Toyota because of the cost and perceived reliability issues, but I completely understand her choice. And I don't see the gasser vs diesel debate much differently than choice between a Toyota and a Benz.
I have had a truck as my daily driver since 2007. I like driving trucks but also need a truck for towing. Back then I towed a smallish boat and a 7k lbs. travel trailer and never considered a diesel because they cost more and I did not think I needed a diesel. But in 2013, we bought a 10k lbs. travel trailer. The gasser would pull it and was within towing and payload specs, but it felt like it was working way too hard on anything steeper than flats. So I went and test drove a diesel and I was immediately sold on it.
After I bought the diesel, it took me about 10 minutes to realize I really, really enjoyed driving it, even when I was not towing. Loaded or unloaded, I loved the torque and the power in the low rpm range that the diesel provided. And as a bonus it also allowed me to pick up a 14k flatbed and a 14k dump trailer for my equipment without worrying about the extra weight; and then because I could tow more I got bigger, heavier equipment. And recently, we traded in the 10k travel trailer for a 20k lbs. fiver, which the Duramax tows with relative ease.
I don't drive commercially and have never tried to figure out if the Duramax was cheaper to own over the life of the vehicle or whether the gasser or diesel is statistically more reliable. The fact is, I can afford the price premium and (at least to me) the diesel is a better driving experience that is well worth any extra cost. Frankly, even if I sold all my big towables, and just needed a truck to commute in, I would never, ever go back to a gasser after having a Duramax because I just love the way it drives.
The bottom line is, depending on how heavy you tow, the Duramax may indeed be considered a more expensive luxury item than the gasser, but make no mistake, the driving experience is luxurious.