I think I know what bikerjames and tourista829 are talking about. There is this man. His name is Cecil. I consider him an itinerant worker. His bike is his transportation. He is a nice enough person. He meeds medical attention for his heart. Most of his teeth are gone. He smokes like a chimney, but is a nondrinker. He will ride his bike thirty or forty miles to a town and work there doing whatever, odd jobs, picking tomatoes, that sort of thing, maybe painting someone's porch. No education to speak of much. He will go to another town say 35 miles away. It may take him two or three days to get there. He will set up his rag tag little camp, stay there so many weeks perhaps, and pick oranges for a living, and so on and so forth. He is a poor homeless man whose only transportation is a bicycle. Or maybe that is not what they mean.
There are people riding bikes long distances who are not what we might define as bicycle tourists. They are people out there on the road, and most likely mainly around bigger cities who are basically down and out. They are not likely to be adventurers; perhaps they are more like misadventurers who are in a hole they do not know how to climb out of. They have their bikes, and that is their only way of getting around. On the other hand, I have lived in China for long periods, and there the velocipede is the main mode of transportation for hundreds of millions of people, and I assure you many many Chinese evince that down and out aspect in their appearances and finances.
The down and out types in the US are not what I consider to be long distance bicycle tourists, but maybe some of them are.