I'm in Tokyo now. It's interesting how Tokyo can still support electronics parts and surplus stores, but Silicon Valley cannot. Granted, it's a bigger, denser metropolitan area, but I'm puzzled that the demand isn't there in California (or New York, where Canal Street was similar to Akihabara 45+ years ago.
I suppose you could say 40 years ago London had Tottenham Court Road full of little electronics shops, the rest of the UK had at least all their local Maplins, all of Germany was plastered with Conrad Electronics, plenty of car boot sales for vac tubes, military spare optics (man, Russia-made stuff in 1990 - great optical quality, built to not just survive a nuclear strike but to be used for yhr counterstrike ... sold for a song), and so on. Nevermind the cornershops for electronic spare parts. Beijing had its block of electronics shops somewhere near Tsinghua University 20 years ago when I was there selling questionable CPUs to retail by the tray (half of them ceramic blanks).
I'm not sure why and when exactly things have changed, but it looks that between pihut and amazon, not much "toyz" were left. I must admit though that the web has made it easier to learn/work alone; you used to go somewhere that taught you how to solder, somewhere that told you resistor color coding, tra nsistor number meanings, yadayada - now you watch it on youtube. The social aspect is gone; even makerspaces are often "just" the 3D printing and woodworking crowds, with little electonics.
It's worldwide. If it hasn't quite reached Japan yet, it will soon enough.
I've seen discussion that it really boils down to tax/rent combination that allows small places to survive on lower income, while the bigger places that would normally muscle then it would have to pay much more.
Greater Tokyo has a population of over 40 million, which is greater than that of all of California (38 million), let alone the SJ-SF-OAK CSA (9.7 million).
Economists since at least Adam Smith have noted that larger cities and regions can support a more complex and richer economic system.
One of California's problems is that rising real estate values and rents are both pricing out more activities (and people), and increasing costs of business: higher rents -> higher wages, the bulk of which are paid to landlords or mortgage lenders.
