Yep, one should budget to buy a new computer every half decade. Seven years max. If you build a desktop you can stagger the GPU refresh and the system components.
Right now is a good time to snag an AMD processor. Not a great time to get a GPU because HDMI 2.1 is still around the corner and that’s going to enable 4K @ 120fps. The 2080 may not have firmware support for HDMI 2.1 (NVIDIA is unclear on this point), and honestly when gaming 120fps is absolutely beautiful. Imagining 4k @ 120fps turns me on.