That doesn't make them fake, in the same way that x can mean 2. You are merely representing a given value (in this case light within a certain electromagnetic spectrum) in a useful way.
Some people see numbers instead/along with colors, and different people see different numbers, so I guess the colors might be different between people too
I disagree that it's pointless. I think it may be beneficial to humanity (eventually) to establish whether or not there is an objective reality which we all experience.