Part of the issue is that when you're young, the school really imposes lots of schoolwork on you, that you can't ignore. It's like school takes over your time, but none of the liability for whether the time will be well-spent. And at this point you don't have good foresight to know the difference.
The more general wisdom I think that should be learned early in life: you always make your own path. Schools are tools for getting there, but the buck stops with you. If you decide to accept a "pre-made path" given to you by a school, you still have to be the one researching whether it makes sense and signing off on it. Just like when you work with doctors, financial advisors, or other contractors, you have to be the project manager of your life's project. Cannot delegate this part. Not easy to learn early unfortunately, but at least start with the understanding that the only thing that matters for economic gains is doing what people want to pay for.