I agree Jet2 is a pretty good success story - they have concentrated on niche routes with little or no competition - that is the reason for their success and nothing more. There is no magic ingrediant. They have as many tech/delays as any other airline - probably more than some.
Indeed. Anyone can start a great, small scale airline and probably can run a reasonably good medium scale one. Running a good, large scare operation is another matter altogether.
Jet2's next problem, should they expand, is that they'll have to try and encroach on the two big boys, FR and EZY - who will fight Jet2 to the death.