We had this guy that used to come to our field that was the same way. Always telling everyone how to fly and what they needed to do. One guy landed kind of hard but nothing was broken. Here he comes telling him "you need to use this mix and that mix..etc." A little while later "know it all" was trying to land his plane and broke the landing gear off. The guy he just flamed walked up and asked him exactly what mix he used to do that. He got the point...haven't seen him since.