I myself am a totally dedicated sports fan and I believe that basketball is the greatest sport on this earth.

dedicated 是动词 dedicate 的过去分词形式作形容词用。dedicate 由前缀 de-（表示"完全"）和拉丁词根 dicare（"宣称、奉献"）组成，意思是"奉献、致力于"。在这里 dedicated 形容人"全心投入的、专注的"，指对某项活动或事业非常投入和热忱。