I think everyone has to make their own decisions. Normally, where I live, I would not evacuate. However, I know the history of the area and of the specific location. However, surge at my home has never exceeded six feet. If suddenly there was a real possibility of 15-20' along the ICW and canals, I'd leave.
So, I'm not one to normally leave, but Florence is exceptional. There are three major risks-the winds, storm surge, and fresh water flooding. The coastal areas of NC and SC are very exposed and the risk goes far inland. Worst case for Florence is CAT 4 when it hits, 15-20' surge, and then slows drastically and up to 20" of rain inland. This storm is equal to the worst to ever hit this area and it's on top of record wet conditions to start with. The point is this may be historically destructive. Therefore, I think a lot of people who have never and thought they would never evacuate have to reconsider it. The hope is they evacuate for nothing. However, we look at Harvey and Katrina and Maria and wish we had done better at evacuating. Starting evacuation on Tuesday is a serious gamble risking looking stupid when it turns out to not have been needed. Not starting it early enough and the storm reaching it's maximum level is far worse though and gets discussion of dereliction of duty.
If I lived there I'd probably have been stubborn and said I'd never evacuate, but I would now likely be swallowing those words and pushing my ego aside and leaving early. Our family in Myrtle Beach has lived there all their life and never evacuated. They're at our home in Fort Lauderdale waiting for us to arrive tonight and join them. I get frustrated when a CAT 1 hurricane is on it's way and everyone is yelling for us to evacuate, but this storm has the potential of setting records. It scares me.
As to boats, there may be a lot lost and it won't be because someone did something wrong or poorly, but because of an extraordinary event.