I used an iPhone 5S until iPhone 8 came out last year. I'm still using a MacBook Air from mid 2012. Do the amortized cost math and it comes out to be way cheape

I used an iPhone 5S until iPhone 8 came out last year. I'm still using a MacBook Air from mid 2012. Do the amortized cost math and it comes out to be way cheaper than the internet & mobile data costs for those devices.