Vega is a horrible example, it was a compute monster and a large reason nVidia created the 1080ti. To this day, AMDs workstation cards are still based on Vega while their gaming GPUs are a completely different architecture.
And the thing about bulldozer is that it sold horribly, it was almost the end of the AMD. While there some unfortunate customers, anyone who didn't buy a 3770k at the time was a fool.
Now, I'd like pose a question. Does AMD even need a 4090 competitor? The 7900xtx is outselling the 4080 and the 4070ti, which is slower than than 7900xt, has cause the xt into a "blow MSRP situation". You can regularly find the 7900xt at $30-50 US below MSRP but they tend to sell out quick at that price.
Now, AMD has an interesting solution to 4090 that it could use if it so desired, it's chiplet design. It would be almost trivial for AMD to make a 4090 competitor but nVidia has already saturated the market with the high end and the sales volume likely isn't there.
But we are also left with absurd level "new old stock" on both sides. AMD nor nVidia has any inclination to make lower end cards or drop prices until their old stock has moved. And there is A LOT of it left to move.
Going back to intel/AMD. Nothing could be worse for the industry than Intel failing to make the AMD fanbois happy. We are not these companies friends, we no longer "customers" we are "consumers" and never forget that