In many European countries you can be "poor" (i.e. have low or negative wealth) while still maintaining a relatively high standard of living. The most expensive asset most people own is their home, so if you rent all your life or have a very long mortgage that you don't necessary intend to pay off (which is not uncommon in some countries) you might have very low or negative wealth. And you might not need to save as much due to socialized healthcare, social safety nets, etc.
Looking at the median wealth (https://en.wikipedia.org/wiki/List_of_countries_by_wealth_pe...), a median person in Spain is 3 times as "rich" then someone in Sweden and Germans or the Dutch are more "poor" than Slovaks or Greeks etc. But this is largely a result of relatively low home ownership rate in most North European countries.
However if we disregard average people and look just at the top 10% or even 1% Sweden is still Remarkably similar to the US:
Wealth Share of the top 10%/1% *
United States: 75.9% / 35.4%
Sweden: 75.3% / 37.4%
Netherlands: 68% / 26.6%
Denmark: 66.6% / 29.3%
Germany: 65.1% / 30.2%
Norway: 65% / 32%
United Kingdom: 59.3% / 24.5%
Spain: 55% / 23.8%
France: 54.6% / 22.2%
...
* according to https://www.credit-suisse.com/about-us/en/reports-research/g..., see page 168 in "Global wealth databook 2019" fro the full table