Fictional Amateur detectives represent the ultimate in tooling. you solve a case in an hour (or as long as your book or tv show lasts) and take a break for the rest of the week. Sherlock Holmes had no other work. He played the violin badly and morphine had little effect on his deductive powers. Mrs. Hudson does the cooking, cleaning, washing, and Dr. Watson is there to lend a ear and keep a watch on his health and boost his ego. And when the right case comes, you turn on your industrial strength detective-lights and save the day and have an immediate impact on ground reality. No nagging women at home. The rest of the time, you polish your skills by publishing 'monographs' on bees, cigar ash, and other important stuff. You have just enough clients to keep this tool-cycle going.
Sounds like a nice job description.