Usually true that they don’t have much of an impact. But there are outliers. At one time in my youth there were two Republicans that I respected. Colin Powell and John McCain. I lost that respect for Powell when he went on TV and lied to get us into Iraq war 2.
But to the point, I lost my respect for John McCain when he took Sarah Palin as his running mate. We’ll never know but it very well could have cost him the election.