Who needs to upgrade to the next device? More likely, you'll upgrade every N devices, where N depends on your personal needs.

This, incidentally, is almost certainly the purchasing behavior of the vast majority of computer owners. RAM and disk upgrades (particularly on laptops) are performed by a fairly tiny minority of consumers. Yet it seems disproportionately cited when shopping, likely due to an illusion of control or the laughable (in computing terms) myth of "future-proofing".

I'm speaking from experience. I'd really like to be able to add more RAM to my MacBook Air. 4GB isn't working out as well as I had hoped. I knew about the RAM being soldered to the MB when I bought it, but I figured I'd be financially able to upgrade by the time the amount of RAM it had became a problem. Unfortunately, I'm not able to do that. I cannot afford to upgrade.

Also, I do upgrade every N devices. I'm not someone that buys the new model everytime they release one. I guess I should have phrased it "because not everyone can afford to upgrade to a new device".

You may be able to sell it, then buy the same model secondhand, with more ram.