I'm not sure that is an indicator of anything at all. You could speculate that people sell their laptops because they want more RAM and that is the one and only reason this is happening. But then that's like what, 100 MacBooks? 1000 maybe? Hardly large in numbers compared to any other laptop from any other brand on eBay.

I know that a lot of people are very emotional about their RAM and SSDs and it can be a PITA, but it doesn't affect as many people as you'd think. At least that's what the available data shows.