In Poland eBay didn't make a single dent because Allegro is such a huge beast(and in my opinion is actually better than Ebay is many many ways), and that's in a country of 40+ million people. Even facebook struggled at the beginning because everyone had a profile on nk.pl so why bother with a new service. Even Amazon still doesn't have a presence, because again, Allegro is the best destination for online shopping.