The reason is simple, You have no business buying a 3090 just for gaming, the benchmarks prove that.
Those who do, are only interested in it as a status symbol, a trophy item, using them just to brag about having the means to get one, on places like this...as the post above this one, shows all too well.
How does it? If you are buying a 3090 like the asus strix, its 20 to 30% faster than a 3080 and 50 to 60% faster than a 2080ti. Will be even more if you intend to put a waterblock on and keep the temps below 50C.
If you are gaming at 4k (which some of us like me have been for 5 years) the 3090 offers you a rock solid 60fps in every game at 4k with max detail (it doesnt actually, if you want to use rtx in control then even the 3090 doesnt give you that but with DLSS on as well it will give you a minimum framerate of 60 fps whereas the 3080 is still only in the high 40s)
With a lot of 3090 buyers having lg 48 cx panels as well, being able to make use of the 60-120 range with the 3090 makes a big difference as well. Some games like doom will be locked on to 120 fps at max detail.