One thing that's struck me reading some of these sagas from L&C to John Johnson is there was no one kind of "mountain man." There were professional hunters and trappers who would make careful assaults into a piece of promising territory to basically grab every piece of value they could. Beaver pelts, hides or whatever they were after at the time. They would go in well equipped and typically operated as a paramilitary team, with the goal of surviving long enough to get their goods and get back to Taos or St. Louis or wherever they were going to cash in. They lived high and the ones who survived made a genuine fortune. Many went into politics or business after that, as we know. They weren't out there to escape the world, but to explore and survey or make a killing. Either way the goal was to get back to civilization in a better position than they'd left it.
Even lone explorers such as Colter had extensive experience with a larger group before cutting loose on their own or in smaller teams. He learned the lay of the land and how to live off of it with the Corps before he explored Yellowstone.
Then you had folks like John Johnson, the liver eater of lore, who came to the mountains well after the fur trade era. He was probably a little out of his mind to start with, and his extreme lifestyle has come to represent the "mountain man" because of that movie. That was NOT how the explorers & trappers of the earlier generations typically operated, though. And reading his saga, I doubt he would have survived long if he'd tried the same stunts in 1820 when the tribes he fought were not yet impacted by diseases such as smallpox.
To group both the famous explorers and wealthy trappers with folk who were frankly societal rejects under the same term leads to a lot of misunderstandings.