Come on guys… People think the sun is yellow because they usually only start to look at it when it's rising or setting near the horizon, and that's when it turns yellow/orange. Few people look at the sun during the day because it's too bright, but look and you'll notice it's white.
Take a piece of white paper outside…it's white because sunlight is white. If the sun was yellow, the paper would be yellow and everything would look like some hue of yellow.