Having heard that, I'd caveat that with "Sometimes, those who have already done, teach."

Which then boils down to the student caution to ascertain whether the advice a solid professor is giving you has changed, since they last successfully did.

And also the observation that the number of students who are likely to be more successful ignoring education is pretty small: most people aren't that brilliant and will get better mileage out of learning and...

also known as those who can't do either (only), comment.