About 35 years ago I was part of a team of independent contractors and we had a problem with our nominal leader who couldn't manage his drinking problem.
The rest of the guys came to me and said you've got to move him out and take his place. So I did. It was him or all of us.
It's not an easy thing to do, shafting someone you've been friends with for a fair while.

I therefore have sympathy for the people in politics who find they have to do the same thing, as Gillard felt she had to do with Rudd & vice versa and as Turnbull just had to do. Maybe they don't all feel regrets as I did, Turnbull certainly didn't look too upset, but life sometimes just dishes these things up to you and you do what you have to.