How so? Their CAPITAL, and decent chunk of territory are on the continent called Europe. a couple tens of millions citizens live there. Just counting those would put them in the first ten-ish most populous countries in Europe.
Good catch :) I'm so accustomed to Istanbul being the center of the Turkey's economy and former Ottoman power. However, that does not change the point. Istanbul and the European chunk of Turkey (+ Izmir and Aegean coast which was in "Byzantine" zone of influence) is a huge chunk of Turkey.