British hairdressers in the 1870s coined the term shampoo from the Hindu champo which translates roughly into "to massage". At this time the British government had taken control of India from the British East India Company, and the Hindu style was all the rage. A shampoo originally was a hair and scalp massage available at fine British salons near you. When the first detergent-based hair product was developed in Germany in the 1890s, the term was then adopted for the hair cleaning product. But that was in Europe.
In America, the hair care industry would not be what it is today if it weren't for one man's vanity. John Breck started balding at age 25. He gave up his career as a firefighter to fight, instead, hair loss. In 1908 he opened a scalp treatment center in Springfield, Massachusetts. (The original Hair Club for Men, I suppose) In 1930 he introduced a shampoo for normal hair, followed in three years by ones for oily and dry hair. By the end of the 30s he was one of America's leading producers of shampoo.
He went bald anyway.