Because a lot of the banks lent all their money to their own builders to build all those houses, to lend them the mortgage money to sell the loan to Fannie Mae AND NOT TO YOUR BUSINESS WHICH NEEDED THE THE MONEY. This is called capital allocation.
Then they sold the crap mortgages to you as a "tranche" and screwed every depositor and investor they could find.
China gaining competitiveness is an EFFECT not a cause.
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