I don't think it matters
I personally think the ps5 can hit the 8 to 10 million range in japan
The system is still relatively new and anything can happen, let's wait and see

A note to nintendo owners: remember when the switch had only just come out and Sony owners were calling it dead on arrival, no one wants it, its just a fad, look what happened, don't turn into them

There are lottery systems for PS5 in many of Japans biggest retailers, it sells whatever sony ships (hence jumping from 15k-35k in a week without any new releases). I'm pointing to one piece of evidence amongst a lot of evidence that supply is not close to meeting demand. You are doing what exactly?

https://www.eurogamer.net/a-tokyo-stores-attempt-to-sell-new-ps5-stock-ends-in-chaos-and-a-call-to-the-police

pointing out that supply is not close to demand doesn't take a genius, seeing as the previous 2 consoles show that most likely another 8 million people in japan would want a PS5

The main problem with people saying stuff like this is that it had nothing to do with reality.  If people called the Wii U dead on arrival then they were totally accurate.  Well, PS5 software in Japan is selling worse than the Wii U.  One thing about being on a website that reports data is that people want an accurate picture of the current sales reality and hopefully an accurate forecast of the near future.  It's perfectly fine to call a failed system, "a failure".

Context is key people were saying not only before the platform launched but on no other basis than their personal preference and not actual data and factors for example it was already known at that point that Nintendo were the only company who would still cater to the portable market in other words a monopoly, this alone made it impossible for NS to be dead on arrival and it's not like this factor was an unseen surprise either.

The context when people aren't impressed by PS5's performance in the region of Japan however is based on actual data we have since it's launched which is over a year ago people have actual charts, tables and graphs with data as well as software performance that they're basing their opinions on the two situations aren't the same.

There's a big difference between not being impressed by PS5 sales and arguing that the demand isn't higher than the supply. I think you're recontextualising the arguments being had here. 

No the context is fine if anything going by the arguments here someone was arguing that demand is as such that PS5 would be the top selling platform for months people just dispute that claim as the data points to that being unlikely if their arguments bother you take it up with them, demand itself is a key factor in supply itself we even had weeks where PS5 performance dropped to like 1-2k, if the demand was the to the point that PS5 would outsell everything else for months it's reasonable for people to think some effort would be made to achieve that for example dedicate more of the WW stock to at least hit 40kish.

Despite dominating the market, Sony have at points shipped only 50 units in countries like spain whilst in the same week their competition shipments have been in the 1000s. Even if Sony could sell 100k units in Japan for several weeks, they can sell those same numbers elsewhere like US/UK where their would be a much higher spend per console. 

If sony can ship 40k to Japan without sacrificing more valuable income elsewhere, I'm sure they would. Unfortunately thats likely well over a year off from being a reality 

Again people are going off over a year of data so their views are reasonable and it's not comparable to the situation with Switch predictions, you can say what you think could happen but so far the numbers back their views and not that of the PS5 being the best selling for months scenario.

My argument wasn't that it will be the best selling for months, simply that demand is pent up and way outstrips supply (which current software sales can't reflect) and a retailer said its 30x higher than current demand, which they did. We know it's supply constraint, so using a year worth of supply constraint sales data is a bit pointless in discussing actual "demand" or peak potential sales we could hypothetically see in a week without contraints. We have plenty of data points to look to like lotteries, being constantly sold out, being sold for high prices on Amazon JP, randomly fluctuating sales according to supply alone, hardware that thats not impacted by its biggest software releases. This mountain of evidence is why their stances demanding "proof" that there is much higher demand than current sales show, doesnt seem reasonable if we're taking the wider picture into account. It's more or less denial at this point.