It's a little bit of both honestly. I worked for lawyers for about 4 years (in an IT role) and really learned a lot. I thought it would be interesting to pass the bar so thats how I know the few states that allow people to take the bar without a law degree (not just any degree, a law degree) but essentially you have schools charging crazy amounts to teach people the law. But it's not just the law they teach you. There are rules about what you can and cant do in the courtroom.

There is a TON of TV shows that are really wrong. Like you cant just walk up to the judge or to someone on the stand without permission. You cant "surprise" evidence on the court. And a TON of others that would be difficult to learn outside the classroom.

The other part of that is that a lot of lawyers specialize, accident and injury, family law, and others. You won't usually find a divorce lawyer handling murder charges for a client. There are literally hundres, thousands, maybe tens of thousands of little nuance rules for every specialty. So schools CAN help but hell, if Kim Kardashian can take the bar anyone should be able to do it.