A person can do a lot of damage to oneself if they go on the internet while in a compromised state of mind. This holds true for anyone.
This is akin to the rule that if you have been drinking or haven't gotten enough sleep, you should not get behind the wheel of a car. When delusional or not in a fully ordinary and grounded state of mind, getting on the internet can damage one's reputation. It is a way that a person can lose friends or blow away business opportunities.
Back on the subject of automobiles, all it takes is one mistake and someone can lose their life or be permanently maimed. Thus, if you are symptomatic with mania, depression, or psychosis, it is not the time to go driving. If you are overly sedated with prescribed medication, you are still expected to use caution and possibly not be in a position of driving.
On the internet, if you post the wrong thing or go to the wrong website, it can do irreversible damage, not only to your reputation, but also to finances. It is easy to pick up a devastating virus from a bad website. If suffering from delusions, it is an additional dimension in which a person can get into trouble. If one suffers from deep depression, things can also be posted or emailed that are regrettable.
About fifteen years ago, I made a stab at self-employment in which I was helping people with their computer difficulties in their homes. I had a customer who was a mental health consumer, and she offered me $100 if I could solve her computer problem (a scrambled looking picture on the monitor). I resolved that malfunction and I collected the money. A few months later, the same customer had become paranoid and accused me of doing something to her computer. She demanded her money back. I refused to comply with that.
My point is that, because of the traits of computers, involvement with them can interact with paranoia. Thus, if you suffer from paranoid delusions, additional caution should be portioned into computer activities.
The internet has been a great medium in which I can interact with a wide variety of people while feeling "safe." The important thing to remember is that I need to catch myself before I send something that's going to "blow people out of the water." When things do not feel normal or when they are excessively stressful, I often stay entirely away from my computer for a while.
When embarking on certain things like internet and driving, it is important to develop a self-warning system which generates a red flag when a mistaken action is pending. When you feel you could be delusional, even if only subtly so, when excessively upset, or when compromised mentally in some other way, it is important to stay off the internet.