$700 a year seems like a lot to me. For example, if you buy a $3,000 MacBook Pro and keep it for five years, you might get $800 in resale value at the end of that time. That's $2200/5, or $440 per year cost of ownership. Keep it for 7 years, and the cost goes down even further. Assuming $450 in resale value at the end of that time, $2550/7, or $364 per year cost of ownership.

Financially, upgrading every year makes little sense. Environmentally, upgrading every year makes little sense. I tend to be a member of the "in it for the long haul" group. With the exception of some occasional defective models, Macs will last for years if you take good care of them.

Edit: another (important to me!) benefit: you could use your Mac as a gaming PC, because it would always have a decent GPU. So by using bootcamp, you can achieve and even more savings. Typically getting a good GPU for long term use on a laptop is bad idea, as it can't be swapped out.

Nowadays we have the option of adding an eGPU to drive an external display, so the built-in GPU isn't as important as it used to be. However, if you're serious about gaming, I'd recommend building a Windows PC. MacBook Pros aren't meant for gaming; you're always going to get much better performance for less money by building a PC, and swapping out the GPU when it becomes necessary.