But how much did the iphone 4 cost? If you pay $800 over 8 years thats $100 dollars a year. This thing only costs $100 every two years.

Of course the TCO of a low-end smartphone is going to be considerably less than that of a high-end model.

Nevertheless, no one is forcing Apple to pour their profits into extended support for older models.

If anything, the incentive is to end support sooner and push consumers to trade in their old devices for newer models.

Well, that high end phone will become low end phone in two years, or even faster if you can't update its OS. So, in this case we are comparing, 2 years of high end phone + 8 years of low end phone against 10 years of low end phone for half the price.

I don't really see what point you are trying to make.

Very few people keep the same phone for ten years; most people upgrade every few years, such that their high-end phone never becomes deemed a low-end unit.

If you're particularly cost-conscious, and don't see the added value of a high-end phone, then buy a low-end phone.