Why do the Irish try to stop development in Europe? (Dublin)

Hi, from Berlin.
I always thought Ireland is enormously gaining strength from the development in Europe and now the Irish do stop the progress of 26 other nations. From the distance the Irish vote looks not very reasonable. Could you Dubliners and Irish tell me why this happened and if you really don`t want to be a part of Europe, why don`t you step out if you prefer to be isolated on this beautiful island - if it is your choice?