Yes it is mostly blue on the scale, but that does not mean it's fucking blue. It means that if you don't see it as purple, then your eye's are not able to discriminate color as well as people who see it as the color that it actually is.
Humans are not very good at discriminating colors, and purple and blue are very much alike in wavelength.
If you can't see it as purple, then you're the one with fucked up rods and cones in your eye, but it's purple.
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