I don't know that John McCain ruined Sarahs life, but he certainly did do a lot to ruin her political career.
I think she would have gone from strength to strength as Alaska governor, and would likely have served two or three terms in that office, eventually becoming a major force in the Republican party.
Perhaps there's still a leadership role for Sarah to fill in the MAGA era. I would very much like to see that.
Any politician who runs for president should be forced to resign their seat since they are useless to the people who voted for them