Italy didn't because it's ports are in the Mediterranean and Italy didn't discover the new world -- Italians did but flying under the flag of Spain or Portugal -- both Atlantic facing powers
In the entire thrust of History you see different forces that move nations
In Sumeria and Harappa and the Nile what was important was to be on a river, not near the sea
At the time of Sargon II to Alexander the important thing was to control the land passages.
Then the Eastern Mediterranean opened up (or rather it always was, but now it became strategically important) and Italia was a back-water
But then, as the Western Mediterranean and British tin trade grew, Italy with it's ports on both the east and west was now strategically important, hence the importance of Rome AND Carthage
But this lasted until Columbus discovered America -- remember that in 1400, the population of England+Wales was 2.5 million, Scotland was 0.5 million and Ireland the same, all of Germania + the Netherlands was 12 million and France was 12 million too --> but much of France's population was near the south as it had always been. Ditto for Spain and Italy's population was comparatively huge - 11 to 12 million and with massive trading powers in Pisa, Genoa, Naples and Venice.
Italia (I use that as Italy was not a united country then until the 1800s) declined for the same reason that other Mediterranean powers declined -- the world passed by them.
Italy was not involved in the 30 years or religious wars and was hardly affected by the Reformation, so their decline, was, as I stated, purely because the trading region passed them by
Certainly the Spanish Empire had the welcome mat out.
There was also the Portuguese Empire, France, and, of course, England and it's interests. Indonesia certainly had room for aggressive young Europeans.