To say Singapore has a higher GDP than any Western country isn't quite a fair comparison. For contrast, the GDP per capita in London (pop 8.5M) which benefits similarly form being a regional hub has a GDP per capita of $73k [1] vs about $55k in Singapore (pop 5.4M) [2].
For a different picture try looking at a figure that looks at household wealth, e.g. household final consumption per capital. These numbers are less skewed by external investment and look at the real purchasing power of average people.
On these figures (US$) taken from: http://data.worldbank.org/indicator/NE.CON.PRVT.PC.KD
Singapore: $12,355 Switzerland $33,284 USA: $31,469 UK: $25,828 Germany: $21,769
By this metric Singapore is far behind most Western economies and is in the same basket as Spain, Greece, Slovenia, Portugal.
Don't get me wrong, the progress that has been made in Singapore is amazing. I just think it is far too easy to be dazzled by high GDP figures, and miss out on the bigger picture.
[1] https://en.wikipedia.org/wiki/List_of_metropolitan_areas_in_... [2] http://data.worldbank.org/indicator/NY.GDP.PCAP.CD