People are just buying the wrong ones, then they get hit with trying to keep them running. I've had 4 Cummins trucks, (96,03,06,12) all with really high miles. (250k-420k) Never replaced turbo, head gasket, injectors, lift pump, injection pump, etc. on any of them. I opt'd to put built transmissions / torque converters in 2 of the 4 for extra performance. They are GREAT engines. The best, bar none IMO
My maintenance cost has always been low for the engines, regular oil changes and a fuel filter change once a year. The most costly maintenance I've had to keep up on for them was the front suspension. (ball joints, wheel bearings, track bar, etc.)