I've given people basically the above points and managed to persuade them. But like I said, only if they ask. Some people don't wanna hear it cuz they think law school is their only possible life plan, so if you tell them it's a bad plan they get mad.
Also you can find out what schools they are targeting and link them to http://lawschooltransparency.com. Amazing to see the jobless rates of students at even pretty good schools.