I'm one who believes that you tend to make your own luck. Apart from PU failures (which could come from having to dog the engine in races because you didn't qualify ahead of the competition), Hamilton has made fewer mistakes the past few years than most of his competitors. Poor old Vettel has hit everything but the safety car and made more unforced errors than Pastor Maldonado used to. And though Bottas has greatly improved since last season, I just don't think that he can sustain an attack against Hamilton over the course of a season. As was shown by Rosberg, that sort of effort is draining on the mind and body. Once Verstappen and Leclerc have more competitive equipment (or Mercedes loses a step), then there will be some real competition for Hamilton.