They crave freedom. Actually, they need freedom. When they don't get it, they are likely to get ill and depressed. As a consequence of their need for freedom, they find special employment situations, or they work for themselves. Look again at the list of Red professions.
Reds are communicators.
They work with words, pictures and sounds. The motivational speaker is a Red. The people who invent your favorite TV commercials are Red. You drive down the highway and a billboard hits your eyes. You drive a little farther and see another billboard for the same product, but this one insults your eyes.