Up until this year scalpers & PS5s being exported was definitely a big factor
In 2021 the average number of PS5 sold per week was just under 19K, while in 2022 it was 22K, normal consumers don't have the patience to go to lotteries or use bots in order to secure a console at normal price - hence its the ones making Y10,000 profit or more on every PS5 that were doing it. Managing to secure 10 PS5 a week that's $700 profit minimum
With the World Wide shortages and demand for PS5s it meant that second hand price was out of control with PS5s being a lucrative item to resell, in some places you would need $1000+ to buy PS5 - that's more than double the retail price in Japan
There have been multiple reports, anecdotes or comments by analysts during the shortage.
Sony Group Corp. has reduced its PlayStation 5 production outlook for this fiscal year due to component and logistics constraints, according to people familiar with its operations.
www.bloomberg.com
By the end of 2022 sales were 2.37M of which I would guess that a not small percentage ended up outside of Japan, simply because of the small number of sales per week making it nearly impossible for normal Japanese people to purchase one at a regular price.
This year supply across the World has improved in a major way making the reselling of PS5 not as lucrative, meaning that launch demand is finally being satisfied as Japanese audience is finally able to easily purchase a PS5 whenever they want it, at retail price or even cheaper second hand.
My educated guess is that the realistic number of PS5 owners in Japan is likely around 1.5M to 2M - this would line up with the fact FFXVI is 50% down while actual hardware sales are very similar to PS4 during FFXV launch
The issue is that in the past three years much of the PS4 audience has transitioned to other platforms like Switch and PC. Even some of those purchasing a PS5 are likely getting it as a secondary console in Japan as its basically a very small niche nowadays that's surpassed by PC market
FFXVI was the high point for software on the PS5 ecosystem this year and it couldn't even help hardware hit 100K - there is no title that is going to launch with over 200K physical sales for the rest of 2023 and I don't expect things to improve next year especially if a successor to the Switch is launching
PS4 had the benefit of competing against one of Nintendo's greatest flops the Wii U and a 3DS that was on the way out.
It had basically every single Japanese Third Party launching games on it and trying to push it as much as they can, many of them as exclusives in Japan(lacking Switch version), most of their investments & marketing were focused on the PS4, as Sony had sold them on the idea that Japanese market was in a terminal condition, they needed to also consolidate on PS4 and leave behind Vita since their portable line was being phased out. And perhaps the most troubling idea was that Japanese Third Parties had to look to the West and compete with AAA Western publishers in terms of dev/marketing budgets in order to continue their growth. Sony would ofcourse push any AAA Japanese exclusive and help with the marketing but it left AA publishers behind.
PS5 is in an entirely new situation where first three years were basically wasted - very little compelling software was released exclusively on the system and now it's likely going to be facing off a Switch successor that's going to continue winning over Sony's traditional partners. Switch already managed to get 90% of AA publishers to either go multiplat or exclusive on it's platform - now the successor needs to address the big boys that have been squarely in Sony's corner. Currently choosing PS5 exclusivity is basically giving up on any decent sales in Japan and sooner or later AAA budgets and marketing will sink someone and rest of the market will react.