What accounts for the increase in wealth in OECD countries?

The ratio of private wealth to income (GDP) in OECD countries has risen spectacularly since the 1990s. This can be explained by: The increase in public debt. But it can be considered that public debt is not net wealth, because it has to be repaid; The increase in asset prices on the back of expansionary monetary policies and the skewing of income distribution in favour of earnings; The lack of a restoring force: the increase in wealth has not led to an increase in demand (a decrease in savings) that would have driven up inflation and interest rates and led to a downward correction in asset prices. It has not been corrected by taxation either.