At the first advent why were professional clergy clueless that Christ was the promised Messiah?

They were fearful of losing their influence,position and how the people looked up to them as religious leaders.They knew the portions of the Scriptures that said the Messiah would come and overthrow all authority and set His kingdom up on the earth but somehow they missed the part of how He would first come as a suffering servant and die for the sins of mankind.And to be fair, some of the professional clergy did end up believing that Jesus was the promised Messiah.Hope this helps.God bless