Brasil is one of the biggest sources of football talents if not THE biggest. Germany and Italy are richer countries meanwhile Brasilians are poor and most of the national team's players come from very poor families (Kaka' is one of those exceptions, he's from a rich family). The only thing those kids did all their childhood was kicking the ball on the streets, in some garden, on the beach. And they are aware that the only way to come out of poverty is to make money by becoming football players. They end up being discovered by the biggest European clubs and then help their families (examples: Ronaldo, Romario, Ronaldinho, Rivaldo, Denilson, Bebeto, Jairzinho, etc...).
^ Like Ziad said, a few kickass teams can be formed and after a couple of years in gaining international experience they can smash whoever you want
luck is only complementary.
GREAT WORK DUNGA!! Next objective: the world cup!