No, not every color exists. While we see a spectrum of colors, this only represents the range that our eyes and brains can perceive. There are many wavelengths of light that our eyes can't detect, and therefore, we can't see the colors they represent.
Think of it this way: imagine a radio. It can only pick up certain frequencies of radio waves, meaning it can only play certain stations. Similarly, our eyes are limited to a specific range of light frequencies, thus we can only perceive a limited range of colors.
There are also colors that exist in the physical world but our brains interpret differently. Color perception is subjective and depends on individual differences in vision, lighting conditions, and even cultural influences.
So, while we can see a vast spectrum of colors, we only perceive a fraction of the colors that actually exist.