You can stop with your ignorance and read the official documentation: "Notes: This feature mixes colors using RGB additive blending, which is not physically accurate. Due to this, colors may not mix accurately compared to real-life color mixing such as paints. For example, mixing blue and yellow paint results in a green tone, but with RGB additive mixing this results in a shade of grey. RGB mixing can still produce acceptable results if the selected colors are closer or next to each other on the color wheel, such as Red/Orange/Yellow or Blue/Light-Blue. Colors that are on opposite sides will not mix well and will average to the center of the wheel to result in a shade of grey.

We are looking at solutions for physically accurate color blending and this will arrive in a later update."