Working While Studying
Well! the answer to this legitimate doubt lies in the fact that the sole purpose of a Study-permit is to allow a student to study in Canada and by requesting to demonstrate the proof of funds the government wants to be sure that the prospective applicant is able to do that without working.
Having said that, the government is also considerate enough to understand the practical aspect it that international students will need an extra income to support themselves while studying. Hence students are allowed to work while studying under certain conditions.
Under What Circumstances an International Student can Work while Studying: