Vancouver also has a pretty high cost of living from Chinese capital flight into real estate, no? Haven't been up there in a while.

IMHO, people think about the nature of capital ecosystems incompletely.

Why haven't other places duplicated SF / LA's ecosystems?

Not because they couldn't, but because they couldn't be better enough to justify the move.

However, "better" and "enough" are relative terms. If SF & LA are executing well, that's an insurmountable barrier due to network effects. But if SF & LA decrease their competitiveness, the relative difference also decreases.

And at some threshold, it does become possible for other cities to capture that business, network effects be damned.