Unlike olden times, communication today has become global. No person is restricted to his/her own country. Be it the education sector- where people go abroad for higher studies. Job-the most common sector where people move out of their country in search of good opportunities.
The pay scale is high; people get to learn many new things when they move abroad. People who seek jobs outside their country often settle there.
Then comes the people who love traveling. They may visit foreign countries, to explore their culture and enjoy life. The reasons are ample. There can be many more reasons why somebody wants to communicate globally.
The underlying part remains the same, that Portuguese should be learned for global communication.