4-1 on Trump is a terrible bet. However...
I think 8-1 on Pence is way worse. I can dream up scenarios where Trump winds up with the nomination. I can't come up with any remotely plausible scenario where Pence gets on the ticket seeing the only people that he could have called his base just wanted to hang him on the Capitol lawn. He's probably not the most hated man in America, but he might be the most widely disliked.