Lasts forever
So that is a common myth... First, diesels have all the same common parts that a gas engine has that are far more likely to fail. Radiator, hoses, belts, power steering, alternator, etc... Those require the same regular maintenance, and have the same odds of failing on a diesel.
And for the difference in cost in maintenance, you could swap out a 5.7l gas block every 150k miles with a new crate engine and still be money ahead! Like everyone else has said, unless you have a need and you use it often for that intended purpose, a diesel is not a good choice.