While I'm not an expert, I believe you are wrong in your assertion that "They almost never had wars, which is good for them right, no war means no money etc to be wasted whereas the other european who were once dominant (england, france, spain ) did have wars."

You are also wrong in that "they never become a 'great' nation." Many historians agree that the Portuguese Empire with their vast global reach was the first truly global empire. In the period between 1415-1580 when they entered into Personal Union under Philip II of Spain, they were the European power with the best technology, knowledge, and experience in colonization. This covered the Americas, coasts of Africa, the Indian ocean, Southeast Asia, and even East Asia.

Following the Iberian Reconquista, the Portuguese tradition of conquest and adventure was very strong, this both led to their successes abroad and arguably their worst dynastic crisis when their young King Sebastiao I and a large part of their royalty perished in the Battle of Alcácer Quibir in Morocco in 1578, against a 1:4 odd in number of soldiers.

When they came under Philip II, Spain was waging war in the Low Countries against Dutch Rebels, and later on also against England's Protestant powers as England's Queen Mary I -- Philip II's first wife -- passed away. This meant that Portuguese colonies suddenly became targets of both the Dutch and English. In this period the Dutch to a large extent copied Portuguese methods of colonization, obtaining Portugese maps, navigation techniques, and Portuguese practice of setting outposts on the coasts for controlling trade. Thus, over the 1600s the Dutch conducted direct warfare against Portugal and her outposts around the world: in the Americas, Asia, Africa.

Back in Portugal itself, there was resentment fueled by the loss of their colonies in Asia, and increasing taxes to support the many wars of the Spanish Empire. This led to war between Spain and Portugal that lasted 1641-1668. Even at the onset, the Portuguese "rebels" aligned themselves with enemies of Spain. They signed a treaty with the Dutch that settled conflict between the two: the Portuguese retained large parts of the Americas and Africa, and the Dutch kept most of their holdings in Asia. Portugal allied with the French, even though later on the French reneged on the treaty. All this set the stage for the the shape of the Portuguese empire, or former colonial holdings, that lasted until the 20th century.