Generally, you'll get better results by spending half as much on GPUs twice as often. Games generally aren't made expecting all their players to have a current-gen top-of-the-line card, so you don't benefit much from having a top-of-the-line card at first, and then a couple of generations later, usually there's a card that outperforms the previous top-of-the-line card that costs half as much as it did, so you end up with a better card in the long run.

Good luck playing AAA titles maxed out in 5 years on a 5080 too... 5090 isn't even considered a consumer card anyway, it's more like an enthusiast, collector's item. It's so expensive compared to its performance value.

You have to look at performance-to-price ratio. That's the only metric that matters, and should determine how much you can sell it for when upgrading, and how often you upgrade.

I don't want to play AAA games now, why would I want to with 5 more years of further enshitification?