I do sell my one year or 5 year old, near mint condition MacBook Pros, to be able to afford significant updates and upgrades. They fetch a good return because they have been kept in pristine condition with product box with accessories in mint working condition. Also buying build to order top of the line also helps keep the resale value at a really decent price. I haven't had any difficulties with that.
I was just brainstorming. If they don't update the screen or the chassis, but only the chips, why won't they offer internals only updates plus labor. Then they could repurpose current innards you sent in, towards their reduced price to clearance refurb$ ?
Their trade in values are decent for the highest possible configuration build to order machines, true.
If I paid say, 4000 to 5000 for my build to order, then after 2 to 5 years people would gladly pay 2200 to 3000 in my track record, for a pristine machine. That is then reinvested in the next maxed out machine, should I need or feel so much desire to upgrade.