Well that opinion is meaningless. If you have diabetes do you get a single treatment? If you go to the dentist for a filling at age 21 is that tooth now sound and you're done with the dentist for life? If you take your car in for a service do you never take it again? We are talking about injury, usually significant, to a dynamic system, the human body.

As for the "affording them forever" meme, that's as ridiculous a statement as I have ever heard. Most people I know visit doctors and dentists "forever" and buy smartphones "forever" and buy food, "forever" What is it about chiropractic services that make ill-informed people expect a Miracle to occur...

Keep attacking that strawman! You can hit it forever! A system that is set to run forever on one input is stalled. When you get new input, it should have a valid output. Each injury would need you to use a system to analyze it (is it something I can resolve myself?) and then a separate system for the fix (bandaid? Surgery? Drug regimen?). It is the same with dentists- a test to determine if the system has faults, followed by corrective action.

Just to flip your meaningless opinion on its head, imagine systems that run forever on one input. The blue screen of death comes to mind. Perpetual motion machines perhaps? In programming, a program that runs forever is in an infinite loop, which is a beginner mistake.