Overseas scalping is also the reason why hardware sales are as high as they are. PS5 was never going to be as popular as PS4 in Japan. But the scalping has made hardware sales higher than they should be and software sales lower than they should be.
What makes you think that?
Because all of the really big (3m+) selling games in Japan are on the Switch. On top of that, most Japanese PS5 games are also on the Switch. For the vast majority of Japan, they can just buy a Switch and be done.