Academic integrity is a permanent proof of one's reliability and ability. Being academically dishonest may give one some advantage in the short term, but it provides nothing in the long term because he or she would not get the educational benefit out of academic institutions and it defeats the purpose of enrolling in a school. The reason we have tests is because we are here to learn and make the most out of such experience, not because we need to get a good grade on it.
Moreover, we do not go to school to learn; we go to school to learn how to learn. College is not supposed to be literally about teaching English majors English, but rather, it's about teaching these students the critical thinking skills that will put them ahead of those who did not have the option to study such things. College education is about four years of learning how to learn and interact with the world. Four years of figuring out how to do things. This is the reason why people who went to college tend to make more than those who didn't, and it's not because society is biased, but because college education makes you an efficient, logical individual who knows who to process information and take what you need from it. Keeping academic integrity is an essential habit that will help you thrive in life.