I think the PCP and genral insame price increase on bikes is what delivers the depreciation in the market. To me, when something is not worth 1/2 the new price 3 years later with not a lot of miles on, it actually indicates that the product was actually maybe not worth the price asked when new. IMO if PCP had not come along then prices would have gone up slowly at the rate of people earnings/how fast they could save for the item they wish to buy. That was unacceptable to the motor industry and along came PCP. Ramp up the prices, keep product flowing through the factories and with money after the 2008 crises as cheap as chips it was a perfect business model.
Now with higher costs of borrowing, consumers with greater expenses (taxation, mortages, cost of living etc), the PCP model isn not quite so pretty and the industry is left trying to sell/rent bikes at sky high prices. With plenty of 2nd hand stuff about and also stuff about that was already good enough for some (was the 1250 so bad that we needed the 1300 reincarnation), the second hand market is the place quite a lot of folk would rather be than taking a fleecing on a new bike (and its potential teething troubles).