The devil finds work for idle hands and there are a lot of idle hands out there. From The Zman at theburningplatform.com:
There is an old expression that has fallen out of favor in the post-scarcity age, but it may be the key to understanding the current crisis. That expression is, “Idle hands do the Devil’s work.” When people do not have anything productive and useful to do with their time, they are more likely to get involved in trouble and criminality. A variant of this is “The Devil makes work for idle hands.” The idea there is if you want to avoid Old Scratch, then make sure you keep yourself useful to God.
The source of these proverbs is unknown, but variations of them go back to the early middle ages, so it is probable they evolved with Christianity. It is not unreasonable to think the idea is universal to civilization. After all, every human society has had to deal with the idle, lazy, and troublesome. Making sure these people are kept too busy to cause trouble is one of those primary challenges of civilization. Every ruler has known that too many idle young men is bad for his rule.
Even in the smaller context, this is something we instinctively know. In the workplace, people with too much free time get into trouble. If the IT staff has too much free time, they start tinkering around with the stuff that is working and before long that stuff stops working and the system goes down. A big part of what goes on inside the schools is to keep the kids and the teachers busy. Home schoolers have known for years that the learning content is just a few hours a day. The rest is busy work.