While that is a part of it, over the past couple of years I have seen way more early 20s collectors enter the market and for them the Copper Age keys are the big books tied to their youth. They have jobs now with decent disposable incomes to chase the funny books that are key to them, and it is not BA or SA. If they follow the trend, they will eventually migrate to BA, SA and GA books, but right now CA is what they are most familiar with and that is what they are chasing. It happened with SA back in the day, then BA, so it only makes sense that demographics are impacting the CA market now as well.
Perhaps there's a Rule that shows what happens to things that came out 25 years previously?
Every. Single. Time.
2 more years, and I can cash out on my Pre-Unity Valiant hoard