Why do foreigners know more about other countries than their own country?

People always tend to go abroad and visit lots of places and they don't know a lot about their own country.

I met a lot of people here in Portugal that wanted to leave their home country to start a new life. I asked them whether they want to return and most of them say that they want to stay in Spain.

My stay in Portugal is temporarily and I'll be glad to go back home. Why do people willingly want to move for good to another country?