Being quiet doesn't have quite the same impact when you're not face to face with people! I think we just like to get our point of view across about a variety of issues, with a view to possibly educating others, or making them think about their life choices and principles/beliefs. Debate is entertaining and stimulating, so it probably brings some degree of pleasure to argue your case convincingly on this forum. "About2Defend" may well be the name chosen by someone who is having their viva shortly. Hopefully arguing points on this forum will provide good training for defending their thesis from the criticism of examiners!