Carrying important items in the backpack is risky

Many people are carrying backpacks because it is more comfortable and does not cause pain. However one of the main disadvantages of using a backpack is that it is not very secure, especially when it is carried on the back
The person carrying a backpack on his back, cannot see what is happening to backpack, especially if he or she is travelling alone.
Most people are not locking their backpack in any way.
So it is observed at the airport and elsewhere that many people with a backpack have the zips of the backpack open
It appears that malicious people are intentionally opening the backpack of people at the airport and elsewhere for fun.
It is very dangerous to have a open backpack, because items can fall off and the backpack owner will not even be aware that the item has fallen off. So the backpack should be used on the back only in an emergency.