You can't buy any Nvidia or AMD GPUs right now unless you're an industry insider because they are selling all of their production to the crypto miners. Yes, you could buy the ones that are being sold for 3-6 times the MSRP, but who in their right mind would do that?
Yep. And another thing to consider here is that the 3090 is a poor value for mining, at least going by initial pricing. It's barely faster than a 3080 for either mining or gaming, but launched with an MSRP over twice as high. So, it wasn't as attractive to miners, resulting in availability being better for gaming systems.
It largely fills the role of what would have been marketed as a "Titan" card in the past, which typically don't sell anywhere near as well as the more "mainstream" cards, being more of a niche product for those willing to pay a huge premium for slightly more performance. But with all upper-mid-range and better cards marked up to Titan-level pricing, the less price-conscious individuals who are willing to buy a card for gaming at those prices are probably going to be more likely to spend a bit more to get the best available option, making the 3090 sell better for gaming than it would have otherwise.
And since the 3090 uses the same graphics chip as the 3080 cards, just with more cores enabled, it's in Nvidia's best interest to direct as many chips that can pass as a 3090 toward those cards (or now the 3080 Ti) where they can make more profit-per-chip, whereas they might have otherwise sold more 3090-capable chips for use in 3080s under more typical market conditions. That likely contributes to making 3080 availability worse.
Why are the AMD fans having a tizzy fit over this? AMD supplies all the GPUs and CPUs to the Xbox X and PS5. They can only get a certain number of chips made. They are Prioritizing the Game Consoles. Nvidia can send more resources to Video Cards. AMD is great, Nvidia is great.
And not only that, AMD needs to also split their 7nm production at TSMC with their currently-popular CPUs. As far as their profit per wafer goes, the large console chips are not likely making them much money, but they need to devote a large chunk of their manufacturing capacity to those orders, as they were undoubtedly arranged with Microsoft and Sony years in advance. Graphics card chip profitability is probably somewhat better, but they are likely being sold to board partners at previously agreed-upon prices, so profitability will be limited there as well. The partners have the option of selling their cards at marked up prices to scalpers or mining operations, but AMD wouldn't be seeing additional profit from that.
Their CPUs, on the other hand, should have far higher profit margins than either, especially with AMD currently leading the market in terms of performance and efficiency, and primarily targeting the higher-end of that market as a result. So it makes sense that any available production capacity that they are not contractually obligated to provide will be put toward their CPUs. So, the graphics card chips are likely getting squeezed out as a result, with only limited production being directed toward them, and it's not surprising to see the market share of Radeon 6000-series cards being relatively low.
For an idea of how profitability compares, the Ryzen 5600X and 5800X are $300-$450 parts, and only require a single 80mm 7nm chiplet, in addition to an IO chip built on the less-expensive and less-limited 12nm process. The Radeon 6800/6800XT/6900XT, on the other hand, require a massive 520mm 7nm chip, around 6.5 times the size of a Ryzen chiplet. And even the more mid-range 6600XT requires a 237mm chip, roughly 3 times the size. And while a finished CPU mostly just consists of the chips and their packaging, sold directly to OEMs or retail, a graphics card chip is sold to card manufacturers who need combine it with VRAM and a lot of other parts to produce a finished card. So while a 6600XT might have a similar MSRP to a single-chiplet Ryzen processor, the cost to produce its chip will be much higher, and AMD won't be able to sell that chip for as much, despite its larger size. So, it doesn't really make sense for AMD to produce any more graphics card chips than the bare minimum that they have to at the moment.
As for the console chips, those are 309mm for the PS5 and 360mm for the Series X, around 4-4.5 times the size of a Ryzen chiplet, and considering that the entire consoles are being sold for not much more than the price of a 3800X or 6600XT, those chips undoubtedly have the lowest profit margins. I suspect AMD might regret having taken on such large orders for them at a time when they may not have been sure how competitive their current PC lineup would be in terms of performance relative to their competitors. Then again, perhaps they consider it worthwhile to keep the console manufacturers using their hardware, in case they happen to fall behind in the future when they might see more benefit from a steady, albeit low supply of income from the console market.