In my previous job I had a lot of contact with people with MI. Whilst I had strong suspicions about my Bipolar, I hadn't been diagnosed and the Dr's had laughed me out of the room (I suspect because I'm very high functioning and well presenting).
In 10 years, I probably saw 3 or 4 people who were the caricature of crazy. Complete rambling drivel, no ability to function in society and a risk to both themselves and others.
In all of these cases, it wasn't so much the MI that was the issue, more the fact that they had abused so many drugs over the years. Obviously the MI may have been a major contributing factor in the initial drug use, but it was obvious that they'd been failed over the years and had been allowed to get to that stage.
One of the 'craziest' was my father's ex partner who he'd met in the psychiatric hospital when he and she were patients (great place to pick up girls!). I'm not sure of her diagnosis, but it's a lifelong illness exacerbated by alcoholism. She recently spent time in prison, I believe for criminal damage or arson. She is someone who genuinely shouldn't be allowed into society for her own safety and the safety of others. I've always been a compassionate, caring person, but I find myself thinking that we do need asylums (renamed perhaps) to care for these people as at the moment we're failing them miserably.
As for me, I have periods of time when I think I'm Jesus Christ reborn, that I'm a superhuman created by the government and that I can achieve anything I put my mind to. Somehow my mask of sanity hides all this from people, but I have felt things have been deteriorating over the years, so this may change! I was only diagnosed in October and I remember highs and lows and bipolar behaviours when I was 11-12. 24 years of untreated Bipolar has probably not done my brain any favours