I can find 2015 retina macbook pros with 1tb of storage that originally sold for 1800 for 600 at this point which is aprox 33% resale value after 3 years. This is only slighter higher than prior estimate. There also may be a transactional cost in moving it ebays cut + shipping OR a time cost/risk in selling it yourself via craigslist for cash. This is not counting the cost of refurbishing to make ready for sale for example replacing the battery. If you spend $30 shipping give ebay 50 and pay 80 for a battery and sell at 600 you may only net 440 or around 25%.
Here is an interesting analysis of why used macs may be worth more. Authors thesis seems to be that because apple lacks a low end and has a smaller pool of buyers there is more demand among cost conscious buyers. It also holds back in 2015 that used apple products are worth twice as much as other vendors products in the same portion of their lifecycle but seems to have hard numbers only for phones and from 2013 so not neccesarily relevant to present laptops.
I further hold that resale value is of negligable value to most uers who will either break a device, pass it on to a family member, lose it, or hold onto it until it is effectively of negligable resale value.
It would be disingenious to take maybe money into account when making a purchase unless you specifically plan to upgrade frequently and use the money from said sale to offset the cost of newer models.
For example one could spend 1800 then sell for half in 2 years and put it towards the next 1800 machine. One could spend not much more than 900 per year after the initial investment. So say over 10 one would have purchased 1 machine at 1800 at year zero one for 900 each at year 2 4 6 8 for an average cost per year 540 per year.
Of course people are vastly more likely to say purchase for 500-900 and use for 3-5 years then rinse repeat for a cost of 100-300 per year.
