Have you taken a university level ethics course before?
They teach the different ethical frameworks, where they come from, and then get you to apply them to different situations. The classes don't tell you what's right and what's wrong, but rather, the different frameworks people can use to determine that.
Is it required that you attend a university-level ethics course to learn how to apply ethical frameworks? Very ecclesiastical. But it would explain why we can't leave this sort of thing to the laity of parents.
In any event, the poster I replied to also included "morality" alongside "ethics", which is why I suggest it's not as cut and dried as you imply.
It's important because ethics is a really complicated subject built on thousands of years of study and thought. It's worthy of being taught by an actual scholar who dedicated their life to understanding the field.
Parents can teach right and wrong, but they seldom teach about things like utilitarianism or hedonic treadmills.
SBF's mom is a legal ethicist at Stanford. Beyond her son, how many others has she mis-educated? Or, perhaps, a semester or two of ethics is insufficient and thus a waste of time and money?
Evidence of individual corruption is not an indication that we should not teach ethics altogether. This is why ethics need to be taught, so that people are better equipped to weed out bad actors.
That said, who did SBF largely derive his ethics from? His parents, at home, not at his mom's lectures. So all this does is illuminate why it's important for people to get exposed to a wider variety of opinions and ethical considerations.
They teach the different ethical frameworks, where they come from, and then get you to apply them to different situations. The classes don't tell you what's right and what's wrong, but rather, the different frameworks people can use to determine that.