And those are only the professionals. You're using a consultant when you ask your neighbor what he uses to remove crabgrass from his lawn. You're being a consultant when your daughter asks you what college she ought to attend. In the United States, at least, you don't have to have a license to advise someone on what car to buy, or to help them find the quickest route to Arkadelphia. My definition of consulting is the art of influencing people at their request.
Many people influence other people without a request.
A judge can sentence you to thirty years of hard labor. Your teacher can assign you thirty pages of hard reading. Your boss can give you thirty days of hard traveling. Your priest can apportion you thirty Hail Marys. Judges and teachers and bosses and priests can act as consultants.