This thread makes me feel incredibly old. My typing class in high school was with an electric typewriter.
But, I'm not old enough to forget what high school was like, and it sounds like your parents have some very real concerns. I don't think anyone would steal the keyboard due to it's value or it's awesomeness (though it certainly has copious amounts of both). It is likely that your parents are concerned with someone stealing it just to **** with you. Which is a sad, but unfortunately, very real reality of many high school environments. If you value your keyboard, and people know it, it instantly becomes a mechanism to mess with you - a means to an end, regardless of value to them. I realize that is incredibly pessimistic, and maybe this is not your experience in high school. I guess you have to use your judgement to decide if there is any risk in the situation. It sounds like you are centered enough to not let someone else's opinion of you sway your decision making necessarily, which is a wonderful trait to have. It is very hard to have a unique voice in an environment that does a lot to silence it.