Agreed, it's a tough sell to have to shell out around $2k every 4-5 years knowing I shelled $2k for a MacBook that ended up lasting 14 years. Adding the upgrades I ended up spending an extra $500. So total $2.5k for 14 years yields a nice $178.58 per year; that's value.
14-years is a long time - impressive! But how many of them were spent wishing you had a better MacBook?
I used a 2003 PowerBook daily for about 7-years, but the last 1-2 years of that was tough with me constantly running out of space and/or dealing with a sluggish machine. I still loved it (and still have it and it still boots!) but really should have upgraded sooner than I did.
Since then I have decided that life is too short to spend it dealing with outdated hardware. Don't get me wrong - I keep things for a good while but also know there comes a time when you have to bite the bullet, spend the cash and move on.