@GeofCox @crazydutchy @DJDarren My personal belief is supported by the impression that the motivation to buy secondhand is different from buying secondhand. Like you said, your decision to not buy new gifts doesn't depend on the secondhand gift market existing or not. You have the spending power to purchase new gifts, but you choose not to, a decision that likely wouldn't be impacted by Santa Claus somehow cracking down on secondhand gifts.
It goes the same way for budget shoppers looking at inexpensive secondhand items. If this market contracts, I believe they are unlikely to suddenly come into enough money to purchase new. So if someone on a budget was looking at secondhand Apple device, if they aren't available, I expect them to turn to a similar priced device which won't be a new Apple device because of the steep price difference.