Geographically, they are very diverse and beautiful lands. Combine that with the opportunity of several pacific-facing ports, and you get a very desireable place for rich people to live. Those rich people then invest and reinvest into local industries, thus producing hollywood, silicon valley, etc. But as the generations who built these behemoths dies out, and is replaced by the generation that takes it all for granted, decay sets in. The current head honchos think everything that was built over the last century is permeant, and that they can endlessly siphon the wealth generated for their own peabrain ideas. Eventually you get what we have now, a much slower but inevitable decay into the next Detroit.