2 plus 2 equals 4. You might be simple enough to need to put two apples in a hat and add two more to see it, most don't.
2 plus 2 always equals 4, whereas not every plausible explanation is a correct explanation. You offered a plausible explanation as to why people would say don't go to law school, and an assumption is needed if you're going to accept that explanation as correct.
Don't worry, I'm not trying to convince you of anything. I'm just pointing out the errors in your logic for anyone who might read your posts and get the wrong idea.