that is only true when talking about the electromagnetic spectrum from an emitter source.
when talking about the refracted and reflected electromagnetic spectrum, which is the vast majority of what we see, its the opposite - all the colors add up to black. this is because what we see is the absence of color : something that appears blue to us is because of the absorption of all colors except blue.
ask any artist what happens if you mix all of the colors available to them… a dark muddy brown black, not white. exactly what soros wants.