Think about it

Why don't Buddhist understand that their  desire of reaching enlightenment or nirvana , and having knowledge is showing that they have a self ? It's within human nature to want to know something. That is a desire. If desiring is the cause of suffering , and suffering derives from self , the Buddhist have a self because they desire knowledge , nirvana, and enlightenment. You've given yourself a goal and live by strict rules and teaching to get somewhere you WANT to be.