Trump winning is the only way Mike Pence ever gets close to the Presidency - he'd be a hopeless 2020 candidate, but hitching his wagon to Trump means if Trump does beat the odds and win the White House, he'd get the spot he's been so obviously itching for in a year or two. How Trump loses the job, you imagine.
Seems as though anyone attaching themselves to Trump's bandwagon is setting themselves up for ridicule and belittlement down the road, from their fellow Republicans. That's far from setting themselves up for President.
Perhaps your comment is true for a lot of other potential candidates. But for Pence, it is really a no-risk option:
1. If Trump wins, Pence gets to play Dick Cheney and audition for President. If he does well, he gets the credit. Otherwise Trump will be blamed anyhow.
2. If (when?) Trump loses, Pence has a better name recognition, than before, and can cash in, either in the private sector or as a Senator for IN.
