The point is it's very difficult for a non-office holder to knock off an incumbent. Yes, Miller managed it but in a very small community of AK and he's the only one who's done it in recent times in a primary. Mourdock was a statewide office holder and knocked off Lugar and Lee won in a convention which Graham has successfully blocked.
Even an office holder will have a hard time knocking off Graham let alone a political newcomer who likely has no chance at all at doing it despite people claiming she has a base. She doesn't and FITS is about as representative of SC as I am (their candidate in the congressional primary got a pathetic 10% of the vote so don't listen to them when it comes to this stuff)
42% of SC did last time. the Democrat party endorsed Graham, as more liberal. The conservatives already broke rank and I think they'd be far more inclined to do so now, post everything.