Cabinet members are looking before the election though. They are out of a job if trump wins. They are out of a job if Harris wins + the Senate. They may not be out of a job if Harris wins and the Senate goes Republican. That’s not good odds to stick around for.
They also aren’t getting regular jobs, there can be narrow windows to join or take months to find something. If you know in 6 months it’s likely you won’t have a job it’s time to start hunting for a new one. It’s likely at least one cabinet member leaves before the election.