Part of the reason it can be hard to tell is because we cannot see a source of the ambient light shining onto the part of the dress we see. The reason I see white and gold is because my brain defaults to the back lighting being sunlight and the overhead being shaded by tent. Not uncommon at rennaissance fairs and the like. But if you see this all as in door lighting it’s much easier to imagine bright overhead department store lights or something.

So no, no one is stupid for seeing it one way or the other.