Criticism can be pretty tough to deal with, especially when you’re still in school because the people hitting you with it are usually your teachers. These are people that you look up to and hope to learn from. It’s pretty common that schools hire the most awesome performers to teach on their instrument, but those performers are not necessarily trained teachers and sometimes you can tell. Things like tactfulness and considering reactions before you speak aren’t always there. So it’s pretty much up to the student to either deal with it or be smashed by it.