On an individual basis, many individual persons do the unlikely thing.
However, for large groups of people, many things about the group are not beyond prediction, despite a few outliers. For example, between a large group of 4.0 HS GPA students and a large group of 3.0 HS GPA students (who are otherwise similar), the 4.0 HS GPA students are likely to do better on average than the 3.0 HS GPA students (in terms of college GPA, 4- and 6-year graduation rates, etc.). It is not a surprise that more selective colleges have higher 4- and 6-year graduation rates, since they have students with stronger prior academic credentials to begin with.