I get the feeling there are those, such as Mattis, who are staying on because they feel like they might be saving their country (possibly even the world) by attempting to curb the most egregious impulses of the idiot in chief. Must be soul-destroying. Got to give them some respect for that.
Tennessee Senator Bob Corker said something similar to that.
I think Secretary Tillerson, Secretary Mattis, and Chief of Staff Kelly are those people that help separate our country from chaos, and I support them very much