The net mean wealth per adult in the US is upwards of $350,000 to $400,000. In Germany it's half that.
The net median wealth is roughly equal (especially after US housing values have recovered, and the stock market is near all-time highs).
Germany only has $50,000 in net median wealth per adult. They are not that rich. France by comparison is nearly three times that; Belgium is three times that; Australia is four times that; Italy, Japan and the UK are over twice that.
Total assets in the US are upwards of $200 trillion according to the Federal Reserve. Household assets alone are nearing $100 trillion (~$80 trillion net after liabilities).