I'm curerently in year 9, going to year 10 next year, and I'm taking up music theory. However, many people say that it is a bad idea, as tehy say it gets extremely hard. Is this true, or are they just scared to lose a class mate?
Depends on how much you know already.
well it does get hard, but you have to know theory to write songs and to get better (unless your some kind of god eg Hendrix)