For anyone curious: the first couple iPhones were subsidized by phone carriers, so the iPhone cost the consumer $X, and the carrier would take care of the majority of it. This was factored into your phone plan price.
Around the time of the iPhone 6, carriers switched to leasing/loan plans. Instead of helping pay for your phone by factoring the price into your plan, they lowered plan costs and started charging for the full cost of your phone.
Prices of iPhone – en.wikipedia.org/wiki/IPhone#History_and_availability
Inflation Calculator – www.usinflationcalculator.com