Companies involved in food marketing are often derisively called middlemen. In almost every society there is a

Question:

Companies involved in food marketing are often derisively called "middlemen". In almost every society there is a belief that the "middleman gets all the profit."
a. Why do people believe this?
b. If the middleman gets all the profit why don't we hear 10-year olds saying they want to be a middleman when they grow up?