And AMD is not dropping prices by much since they moved to TSMC. Ryzen 3000 still retails for close to MSRP (10% less at most) even though both the octacore and hexacore 3000 series cpus are losing to both 10th gen and 11th gen Intel parts as well as to AMD's own 5000 series parts. AMD at most will reduce the prices of 5000 series by 15% and even that will be in a firesale way during Intel's launch and then when they release the 3d cache parts.
Actually, Ryzen 3000 chips dropped to well under MSRP prior to the 5000 series launch. For much of 2020, you could get a Ryzen 3600 for around $170-175 from multiple online retailers, and sale prices occasionally got down around $160, or 20% below MSRP, for a chip that was already a pretty good value to begin with. Likewise, the 3700X worked it's way down to around $275, and there was apparently a brief sale that brought it as low as $260. Only when the 5000-series launch was approaching did prices start to rise again, likely as AMD moved their 7nm production to the new Zen 3 chiplets. The 3000-series prices you see now are likely down to the limited supply of remaining chips, as I doubt AMD is still manufacturing these processors in any significant quantities at this point.
5000-series pricing was quite high for a given core count, though the reasoning behind that makes some sense. Their 7nm production was limited, and a lot of that had to go toward fulfilling their contracts for large console chips, and at least some needed to make its way into GPUs. And since their processors were superior to Intel's existing offerings, they knew they would be in short supply. And sure enough, even at those higher MSRPs, they were in such high demand that it was hard to find them in stock for months, so that was arguably a reasonable decision.
However, if Alder Lake regains the performance crown, which seems likely, demand for Ryzen 5000 chips will drop in the performance segment, as should their prices. As it is, the 5600X was already on sale for under $270 multiple times during September, and the 5800X has been pretty consistently available for around $390 for months, close 15% below its original MSRP. And keep in mind, AMD is still making large profits on each of these processors, and has lots of room for adjusting prices downward, as they don't really cost any more to manufacture than the 3000 series did. The updated "3D V-Cache" parts may allow them to better compete with Alder Lake at the high-end, but those won't likely come until a number of months later. And that still leaves existing parts in a position where they will need to be discounted. And if the stacked cache costs significantly more to implement, existing designs might manage to remain viable at lower price points.