Why is Brazil not a Great Power?

Looking at a world map, you can clearly see that some regions naturally learn towards regional multipolarity, while others lean towards regional hegemony.

For instance, in Europe (without the EU), Africa, the Middle East, these regions are structured in way where there's not one single country that can dominate its region through its sheer size.

This is not true for East Asia (China), South Asia (India), North America (United States), Oceania (Australia).

So why is Brazil not that important? Its population and size dwarf that of any other country in its neighbourhood.

While I admit that I do not know much about the country, my personal theory is that 1) Its internal problems (weak economy/corrupt system) and 2) America is so powerful that it exerts far more influence than any potential challenger in the Western hemisphere.