By witness I mean seeing something amazing with your own eyes not from indirect sources. I was talking about them as it's related to the event of a "what if" asteroid impact of a big and dramatic scale. I'm proposing it will do good to witnesses mental health, potentially. I think it's an interesting point to make which other people might not know about. As I say it's a recent medical theory. The theory still applies to other things less scary but still impressive, to view peacefully the Grand Canyon has also been suggested to possibly be enough awe to some people to change their mental outlook.
In regards to anarchy and gangs, though I said that would be better than just being depressed, I would not suggest a person would suddenly become a gang member or commit crime if they have reasonable choice in the matter. gangs/anarchy were your words so I responded to them.
Also I dispute you declaring crime as not being healthy. It can be perfectly healthy in a society or group or even as an individual that accepts it as a normal way of life. You are using blinkered thinking to say crime is unhealthy as you are so used to what crime means to you and your culture, and in fact most human cultures. But that does not mean it is impossible for it to be healthy.
Crime is highly successful and evolutionary for those who get it right. A nice example of this is the male penguin as seen and reported by Frozen Planet on the BBC,
http://www.bbc.co.uk/nature/15305502. But of course this crime is apparent with all kinds of creatures and animals. In the right environment for humans crime can be a healthy norm, it would still be highly disapproved of if caught though by victim, as in nature.
The example I linked is of deliberate and knowing crime, it knows it can get caught and it knows to try and evade getting caught and to stop others stealing from him, just like he steals from others.
This penguin is decent healthy penguin. Or are you suggesting this penguin is wrong? This penguin is highly in control of it's life.
Oh and I would say that if a person found a life of crime stressful for any reason then yes that would be unhealthy. But if they were neutral on it and had self worth invested in the prospect of crime they would have a good mind.