One of the documented side effects of virtual reality is a mental disease called derealization , which makes people feel like real life isn't real, and causes a lot of anxiety.

Also there's the fact that military training conditions people to kill automatically without thinking and the fact that virtual reality has a proven ability to decondition people with PTSD or fear of spiders(with real results in real life), which is basically the same psychological process of military conditioning.

All this raises interesting questions about "the line" between real and virtual , that at least be tested before wide scale deployment of VR.