I love all the responses about how folks are able to prolong the lifespan of their older Mac hardware (I'm running a 2010 MBP myself). I imagine that's part of the problem -- Apple sells more hardware if you can't upgrade.
Not necessarily. I used to get the newest model every other year. Following the discontinuation of the 17" laptop, I held onto that until it died, only then buying the newest MBA. On the desktop side, my Mac Pro is eight years old now, and it has long been upgraded as far as it can go. Sometimes I miss things like AirDrop from my phone, but I don't miss them enough to spend money on what is effectively a downgrade in usability. I'd love to upgrade and have no issues spending the money in theory, but I can't justify the expense for the current hardware.
I bought 6 separate Apple machines between 2005 to 2012. Either because the upgrade was worth it, I had a nice bonus, or some other non-important reason.
The last piece of Apple hardware I bought was a new mid-2012 Macbook Pro. After seeing where Apple was going in 2013 / 2014, I have had zero desire to replace it. I upgraded everything in it, and replaced the optical drive with another SSD. I'll be sad the day that thing finally dies. I'm not sure if I'll go with another Apple machine or XPS with linux. I really don't want it to die lol.