I think you misinterpreted my point. I didn't say a nicer laptop made me 10% more productive. The real number is likely much higher than that. I gave 10% as an example where it would still be worthwhile to pay $1500 for. Considering the hourly wage of a programmer, 28 cents is a rounding error. Yes the returns are diminishing, but they're still totally worth it.

With regards to being able to buy more equipment: I do have a powerful rack-mount server in addition to my MacBook. But being able to buy five ordinary laptops for the price of an amazing one? That's not very relevant. I can only type on one keyboard at a time. If anything, more laptops would slow me down. I'd have to keep all of their software up-to-date, sync data between them, ensure their batteries were charged, etc.

Imagine making the same argument in other domains. For the price of one plane ticket, I could buy five Greyhound bus tickets to the same destination. For the price of one quality memory-foam mattress, I could buy five innerspring mattresses. For the price of one Aeron chair, I could buy five AmazonBasics office chairs. So what? I don't want more. I want better.

If you are paying for Applecare, you are paying for "more not better". A second laptop is zero (amortized) overhead: every night your real laptop rsyncs back to the spare. Battery floats at 70% charge, nothing to worry about there either. Now when you spill coffee all over your laptop, you have a hot spare ready to go. If you are accident prone you can do this "for free" up to four times. Imagine the productivity gain not having to visit a store and deal with the Geniuses.

It is irresponsible to always buy the "best" when you should be looking for the best value per dollar. Your own bank account is zero-sum, be more effective with it.