It's quite something to see people looking down on the standard of living in Japan

I don't understand why they think they are so vastly superior. You'll eventually realize that it's not even that common to find foreigners living with a lifestyle as "Korean-style" (in a positive sense?) as what you see in Japan. Since personal vlogs have been a trend in Japan for five years now, there is plenty of data.
Whether it's Ireland, which has long been a legend that is hard to even approach in terms of GNI, or Taiwan, which is amazing in terms of PPP, or the legendary trading city of Hong Kong—the reality is that if you actually look at the daily lives of ordinary people in those places, it's hard to find anything significantly superior to Japan, which is criticized almost every day on forums.
Let me state one fact: there are many successful businesses related to construction and architecture in Japan. You could even say it's a widespread phenomenon. If things were truly dire, those kinds of businesses would be the first to collapse. Besides, it's not a culture of liking to show off to others; it's just for their own family's satisfaction.
And while the exteriors might lack even a sense of human touch (which is true; looking at the outside of the houses, they can feel like factories for specialty crops?), the interiors are often decorated in a very "green, green, wood, wood" style. Arguments like "How could they afford that! Look at the GNI charts! Look at the charts!" don't work, because Japanese renovation companies are actually booming.
There are certainly men and women living in this manner, and there are more of them than in countries where people on forums just give a thumbs up based solely on looking at economic charts.