Overpriced phones might be a cause
I upgraded this year. Had my last phone roughly 2 years. Had no intention of upgrading, yet I was able to get a 5.3 inch, dual low light camera that sees better in the dark than I do, 32gb x 2gb RAM, quad core, with high res screen, no cost tethering, unlimited everything all for the price of one month's, no contract payment.
In other words the phone was free.
What was once a high end, then mid-range and now budget phone is a giant leap forward compared to my last phone from just 3 years ago.
Hell no I'm not paying $200 plus for a damn phone.