I'm not so sure, a good second hand RTX 2080 is still listed for a lot more than I paid for it brand new.
According to my Amazon history, I paid £369 for my RTX 2080, which was an upgrade from a GTX 970, which was also an upgrade from a GTX 760...and so on. As you can see I went from a relatively low end card in the 7x generation to a relatively high end card in the 20x generation, because that was the only way I could see some sort of tangible jump in performance. Going from a 760 to a 960 wasn't that much of an upgrade, and going from a 970 to a 1070 wasn't much of an upgrade either. I went from the 970 to the 2080 because I wanted to bump up to 1440p (which is the resolution sweet spot as far as I am concerned, 4K is just weird for work and desktop use).
I think the RTX 2080 has caused people like me to switch to a two cycle GPU upgrade pattern rather than a one cycle because the actual benefit of upgrading has got a lot thinner in recent years. Going from a 2080 to a 3080 wouldn't really change anything for me apart from the power consumption! I'd still be at 1440p, I'd still get framerates under the 165hz in more demanding titles and so on.
The jump from a 970 to a 2080 wasn't as massive as some people might think it is. The 970 was and still is a solid 1080p card...my oldest son still uses the 970 and for everything he wants to play runs absolutely fine around 60fps...what I did to squeeze a bit more life out of the card was put him on a 1050p (1680x1050) monitor...so from a casual glance, it looks 1080p, but it's a big enough jump down in resolution that it allows the 970 to stretch its legs a bit more. The visual difference between 1650x1050 and 1920x1080 is marginal at worst, an entirely unnoticeable at best.
If we go way back to the early GPU days, upgrading from a Voodoo 2 to a Voodoo 3 was compared to today a pretty massive jump.
You also have to factor in that the difference between a top end AMD card vs a top end NVIDIA card doesn't actually matter anymore for the vast majority of people.
The majority of people are also still gaming at 1080p because we haven't yet seen the leap in the mid range cards that allows for consistent performance across the board at higher resolutions.
Even top end cards don't really get past 60fps at higher resolutions in most AAA titles. The 3090ti paired with a solid CPU can only barely top 100fps at 4K...in GTA5 (an ancient game at this point) if you turn MSAA off.
If you have to run a card that is two generations old at 1080p, you're going to get around the same framerate...so whats the point in upgrading if you aren't going to go 4K, if 1080p is good enough and you're going to see bottlenecks with higher end GPUs on mid tier systems?
My advice to anyone out there considering buying a new GPU for a bit of a performance bump is to forego the GPU upgrade entirely and move from a 1080p display to a 1050p display. You'll get the same performance jump that you'd see if you bought a new GPU for a fraction of the price. In day to day use you won't notice the difference...if anything you might find it more comfortable to use because 1050p is 16:10 aspect ration whereas 1080p is 16:9 so you end up with what feels like more vertical desktop space.
We're living in strange times right now, and as weird as it sounds...downgrading your monitor just a touch will get you a better performance uplift than upgrading your GPU.
Even better, most 1680x1050 monitors are 75hz...so as an added bonus, you also get a higher refresh rate. Going from 60hz to 75hz is a significant and noticeable change in games that support changing the refresh rate...it certainly makes a difference in games like CS:GO, PUBG etc.
There's one as an example.
So for £49 you can improve your framerate significantly with barely any visual loss in detail (in fact you might be able to push texture detail higher because of the VRAM you save on the resolution) and you get a higher refresh rate. That's the dream right?
If you're smart, and you want to improve performance of your existing rig...take a look at your monitor first before you buy a GPU. You'll save tons of money and probably get a better uplift in performance.