Why don't you become a teacher?

I always see/hear people around me bit*h on about my wage and my holidays and how easy my job must be, but never see any people sign up or stay long. There must be a reason or two Melbourne is in such a shortage, no? If you're one of the people who think teachers are paid too much, or have it too easy could you please let me know what's stopping you from doing it yourself? Just curious. My brother doesn't believe me when I complain "you earn more than me shut up" thoughts?