I'm self taught, learned on a Sim and an Ultra Micro T-28, then maidened a solo's an Apprentice. I have a friend who helps coach me at times, but now with about a year of flying, I can take my Kadet, do touch and goes and land like a big bird upwind and down wind clock wise and counter clock wise.
Do I know everything, heck no, so I ask. I haven't joined a club since I have no need to, I fly at my friends place with a couple other guys, and his neighbor sometimes flies from his house down the road and encroaches in our airspace and we chase him off with our planes. It's a hoot, and something you wouldn't get from a club.
One thing that helped me is not having to worry about other people getting in the way, or me getting in their way, or doing something stupid because I didn't know the rules or something along those lines. However, not everyone has a 5 acre land out in the country to crash and learn in, so going to a club is the BEST thing for them, and I support that fully.
The difference between me, and the guys the OP posted about is I ask questions before I sink any money into it. Want proof, look at some of my posts regarding certain types of planes. I want to make sure that what I am going to buy is something that I can fly. I have a Blade SR still sitting in a box because I thought I could eventually learn to fly it, and after flying a Blade SR 120, I gave it a whirl, and promptly put it into a wall, so back in the box it went after I repaired it, and haven't touched it since.
Now time warp into the past, back in the 80's when I thought I knew it all, I was the guy the OP talked about, and I quickly learned that I didn't know anything when it came to RC flying. I also shelved it for a long time, mainly because I couldn't afford it, but now that I can, I make sure I wont wreck it, or hurt my self or others.
So in a jist, some people can learn this on their own with patience and the right kind of practice, and time, but if you want to get right into it, no better way than to join a club.