Answer:
Hong Kong's economy was able to sustainably grow at very high rates during a long period of time. This means that Hong Kong's GDP per capita will constantly grow, so even if it started at a very low level it eventually grow to much higher levels.
Meanwhile, in Argentina and Venezuela, the economic growth rate was very small, sometimes even negative. Their GDP per capita may have been much higher than Hong Kong's 50 years ago, but since it stagnated for so long, it didn't grow that much.
