It is patently obvious, and Greenspan should know this, that any increase in paper wealth cannot translate into spending unless the assets are sold. Failing that, then increased spending must come through borrowing. Probably because the wealthier people feel the more confident they feel about borrowing. But this does not explain any increase in spending. If the borrowing is real, i.e., it comes out of the income of others, then total spending remains unchanged because increased spending through borrowing must result in decreased spending by lenders.
Real borrowing is the key.
What consumers have been borrowing is not the savings of others but newly created bank deposits courtesy of the Fed's credit expansion. This is why consumer spending was booming. However, the process is not quite this straightforward. Now I am perfectly prepared to believe that people have been encouraged to borrow because their paper assets increased in value. The same thing that created the credit to fuel the consumer spending boom.