As any true-blooded Irishman, which I am not, will tell you, the Irish have not had a particularly lucky history. This is where the term luck of the Irish applies to their long history of bad luck including conquest, famines and annoying leprechauns. Despite their unlucky history,
and the Irish seem to be able to bounce back. Ireland
It appears that a likely origin for this phrase comes from the United States. During the gold rush many Irish people headed out West to find their fortune (or pot o’ gold). When the Irish arrived many did not like them and the Irish were generally treated badly. When the Irish found gold many would simply attribute their discovery to dumb luck instead of their skill. This is how the term luck of the Irish can also be used for someone who has dumb luck.
This St. Patrick’s Day when you utter the phrase luck of the Irish you can attribute it to good luck, bad luck or just simple dumb luck.