If you want something deadly with 3 wheels get yourself a mid 80's Honda Big Red. It's not road legal because it's an ATV, so you die like a real man, 50 clicks down a bush road, and eventually get eaten by a bear or bobcat. Most insurance companies won't insure them because they have a bad safety track record but they're a lot of fun.
Those balloon tire three wheelers were notoriously unsafe, yeah. I remember riding on the back of one several times when I was young, and always feeling like it was about to tip backwards (which they were prone to do). They also liked to tip over (to the front) when turning.
However it's also reasonable to say that people who "can't physically handle" riding a motorcycle should stick to using a 4-wheeler to get around. (even a tiny car is 1000x safer then ANY bike)
But but but...I want the wind in my face! And bugs in my teef! Y u wanna limit my enjoyment, bro? lol
To answer the question in OP/title:
In my area, I see more middle age to older men riding them, and the majority are white