Pence had a real chance to be President of the United States if he declared Trump to be mentally incompetent under the 25th Amendment. He didn't take it. So now he will never be President.
Most people never get a real Shot at being President. Even established politicians who try to run are, at the moment they declare their candidacy, more likely to lose than to win. Pence had a clearer more certain path than almost anyone else ever gets. He blew it.