Jeff Berwick touched the subject rather well, Here, and here.

• A lot of the "big earners", have build a following over years and years of hard work, sometimes even with absolutely nothing to show for it.

Larken Rose for instance, have been selling really cheap copies of his books, sometimes practicly giving ekstra away for free, if you bought one, just to earn a tiny amount of money in order to continue the work that he's been doing, which he have been given away for free, for years.
The Mirror which is probably his biggest project to date, is also something he's giving away for free, once it's done.

^ The same with Jeff. He have 2 youtube channels, The Anarchast, and, The Dollar Vigilante, where he's been consistently producing great stuff, and just giving it away.

• It have definitely been a lot of work. So I think it's completely fine, that they earn something now. (I've been following them both, and a couple of the other "big earners" for years, without paying a dime. - Well, I've donated a little, once in a while, when I could afford it. But voluntary donations, doesn't change the fact, that they give it away.)

So as Jeff writes in one of the posts, "Take note of what they do, what gives them success, learn from it, improve your own work, and build a following that way." - Though I'm paraphrasing a bit, but it's around those lines. ^_^