On 1st January 2002 countries first started using Euro bank notes. The year before Ireland was ranked 13th out of 195 countries in the world for GDP per capita.
https://countryeconomy.com/gdp/ireland?year=2001
That doesn't sound like being light years behind the rest of Europe to me. Ireland adopts a very competitive corporation tax rate, which attracts a lot of investment. That is a much better explanation for Ireland's success. That may not last forever though - the EU has plans to harmonise tax rates across Europe. This will cause tremendous damage to Ireland.
https://www.irishtimes.com/business/...exit-1.3220094
I already said that countries have to take some responsibility for their problems but the euro strait jacket exacerbates them as I explained. Some countries can compete at the same exchange rate but others quite clearly cannot.