The SAT, by design, covers the entire difficulty range. Parts are easy, parts are hard, such that about half of students get less than half of it right, and 0.1% of students ace it. It's not merely pass-fail, they're trying to give a pretty granular rank to each student.

Thus, if the test is worth taking for a student (because they want to go to college), it's probably worth cheating on. Students outside the top 0.1% can appear better than their peers to improve their odds of getting into better universities, and students in the top 0.1% tend to be there due to intense extrinsic pressure, which may drive them to cheat to increase their certainty of acing it.

For a competent student, it's not hard to get an acceptable grade. For every student, it's difficult to achieve an exceptional grade.

It is not hard for many students to get a pretty good score (1350). But a score like this will not help you get into a top school, and might actually hurt you. Even having a very good score (1530) does not necessarily help you much, especially if you are from what is perceived to be a high-resource (wealthy) area. If you have a perfect score (1600), that would help you get into any school.

Admittedly, it wouldn't help that much if you are Asian and from a wealthy area, but if you cheated then you could spend time that you would have spent studying for the SAT instead doing something else that you could put on your application.