I've said it before: Trump is a forrest-gump like character. Below average intelligence, but he's been successful more due to luck than anything else. He was born into a wealthy family, which gave him early advantages in life. The wealth that he obtained through family connections helped him buy himself out of problems early in life. More recently, he seems to have been supported by Russians, likely as a front for money laundering (you don't need much intelligence to be a stooge like that.) He was picked to be the host of The Apprentice, despite not being a very capable businessman (and despite the fact that he didn't actually create the show.) When he entered politics, he won the Republican nomination, mostly because they had 'clown car' primaries (i.e. lots of candidates, so easy for someone to sneak in even if they don't have widespread support). And he won the election thanks to the assistance of others (Russian interference, Comey's pre-election surprise, etc.)
Trump succeeds by either being lucky, or being a pawn to others.