I will second what MrN1ce9uy said. You could buy an $800 GPU now, likely stay over 120 FPS at 1080p for five years and then in five years, the other $800 would buy a GPU better than an RTX 4090. The 4070 Ti is faster than the best gaming GPU of five years ago, the RTX 2080 Ti.
And not only do you get more efficient GPUs for your use and a better one in the back-end of the years, you also get more warranty coverage (six years for the two GPUs instead of three years for just one) and access to the specific technologies that are implemented in the next five years that may improve the experience. Not to mention that the 4090 is more likely to be dead in years nine and ten than either of these GPUs in years four and five.
Buying the most expensive GPU to keep it for a decade makes *zero* sense. It's a worst of both worlds scenario: you're paying a lot of money to get great performance now that you can't use and average performance later that you can get far more cheaply then. It's the equivalent of ordering a cheeseburger now that you intend to eat in three weeks.
Buy the GPU you need now, not the GPU you need in five years. There's no financial or performance benefit to doing it this way.