The answer is not easy. Figure 1 show that there is a positive correlation between the total growth in population since 1950 and the total GDP growth (data borrowed from the Total Economic Database run by the Conference Board). The countries with rapidly growing population get higher GDP growth rate. However, when the GDP is replaced with the GDP per capita in Figure 2, the growth in population seems to be a negative factor for personal prosperity. The U.S. does not demonstrate any superiority over any European country except Switzerland. However, we have to take into account that the level of GDP per capita in 1950 was almost the highest in the US and Switzerland.
Figure 1. The total growth in population since 1950 vs. the total growth in real GDP
Figure 2. The total growth in population since 1950 vs. the total growth in real GDP per capita.