As you known, Byzantium settled opposide side of blinds' lands. That's a lovely also a little part of romantic history. The land of blinds is Chalcedon(today's Kadıköy) which is another Megara colony and I think people in there don't deserve to call as blind.
First of all they have strong defence against Thracian attack (They were located other side of Bosphorus). I think it is the main reason why they settled there. Secondly they have water(streams) also natural ports which are safe for strong north-east wind
By the way, Fikirtepe is in Kadıköy so probably there were people in area before Greeks colonists