I'm sorry if this ends up being a dumb question, but I have been pondering it the last couple days.

In our day we have a literal wealth of information on correct poker play. From a recent surplus in publishing of quality books (and some not so quality) to heaps on information found on the Web (some of the best found right here) any person with enough will to succeed can find all the information needed to improve his game abd be a winning player.

But what of the players from earlier, even just a few years ago before the poker boom? For example, Phil Ivey. Granted the guy's gifted, and that plays a big part, but even the most gifted person isn't born with a knowledge of pot odds, positive EV, hand reading skills, and the like. How did these guys learn the game so well without going broke a 100 times in the process?

-edited-
Also even the earlier players like Doyle Brunson and his crew from the good ole days? Where did they get their poker strategy from?