Why Argentina is such a developed country, but so poor?

For a Latin American country, Argentina has a great HDI, ahead of European countries such as Moldova, Georgia and Serbia. The public education/health system is also better than that of neighboring countries, like Brazil or Peru.

Well, Argentina is a "developed" country.

But why are so many people in Argentina poor? From the looks of it, it is a country with a good quality of life. Looking at Google Maps, I notice that almost all the cities are well planned and have good urban infrastructure.