Some are just “Not fit to teach!”
As a martial arts practitioner and an instructor, it is often easy to let things get to one’s head and start to think “my school/art is the true way and the best way!”
The world is a very large place and martial arts is never about one school, one style!
For one to bad mouth another, especially as the head of a school, only shows the lack of mental and character training. If one bad mouths other schools in order to retain students or to make him/herself feel good about his/her school, this person is really NOT FIT TO TEACH! 「指導者として失格だ!」
If you feel threatened, re-examine your confidence in your own art. You can either train harder or simply give up. Your choice. Living a life feeling threatened is no way to live at all. Be better, better than others and most importantly be better than your previous self.