A: If someone came to you asking for $1000, the keys to your car, and your credit card, you would probably want to know what they were using them for. Not so different for your school and work.
When you are at school or work, you may be using their computers, software, hardware, network, or broadband. These are valuable resources that must be shared among all users.
Imagine if a few people decided to watch streaming 4K movies using these resources. These movies can take up to 15Mb/s bandwidth for each movie. If the school or work has a 50Mb/s Internet connection, 3 people streaming will choke out all other use.
There is a darker side to this issue as well. Schools and workplaces have a legal responsibility to ensure their resources are being used – for lack of better phrasing – for good, and not evil. If a student or employee is conducting illegal activities using the school or work resources, everyone gets caught up in the legal process.