The fact Canon is doing well is besides the point. Canon has literally been pushed into being competitive. It's Sony who has done this because of the of all the things I have mentioned before.
That is backwards. Was the timing of Sony’s launch of FF MILCs a coincidence? They had already drastically reduced their DSLR line in favor of APS-C MILCs because they were not able to compete for DSLR sales with Canon and Nikon. Then, the 800 pound Canon entered the APS-C MILC market with the EOS M, and Sony shifted focus to FF MILCs. About 5 years after Canon launched the M line, it became the globally best-selling MILC line. Canon launched their FF MILC line in 2018, and since then Canon has steadily gained FF MILC market share, to the point where they likely are or will soon lead the entire MILC market.

So really, it’s been Canon pushing Sony to be competitive, not the other way around as you suggest. Sony needs to stay one or more steps ahead just to keep from losing more market share, and they’ve definitely been innovative. Given the trends recently (the real ones extrapolated from actual data, that is), Sony is losing ground.

Even studies/stats are nothing more than asking a small percentage of people their viewpoints, sometimes only a couple hundred or less are what studies can be based off of.
Yes, data can be obtained from relatively small samples, but one critical criterion for such studies is that the sampling be random. Drawing a conclusion about the general population of camera owners based on a small number of people who’ve chosen to sell their gear online simply is not valid. I realize you’re probably incapable of admitting that your observations are anecdotal, but they are.

When it comes to the R3, look at it from a person who is not heavily invested or in my case most of my gear stolen and only have a few things left.
Can you honestly say you believe that most people who would be considering an R3, a1 or Z9 would be ‘not heavily invested’ in a system or have had most of their gear recently stolen? Sorry, but it seems completely unrealistic to me that any meaningful number of people considering one of these cameras costing more than $5500 would be in that scenario.

As I stated earlier, if you want to buy an a1 or the Fuji MF, just do it. Why should anyone but you care? Whether switching is as common as your observations suggest or not shouldn’t matter at all.