Because it started as a way to troll the libs by pretending it was a white power symbol. But then actual white nationalists started using it and it's not entirely clear if they thought it was a joke or not, so it sort of became a hate symbol sincerely, except it's also still used ironically.

I don't think she was doing anything intentional with her hands, it was probably incidental and there's no reason to read anything into it. Particularly since we don't need to analyze secret hand signals to determine if she's a racist or not, we can just look at who her friends are (Stephen Miller) and what policies she supports (ending birthright citizenship and stripping the children of immigrants of rights) to conclude that she is indeed a racist.