Eve Online taught me that math + leadership are effective ways to win. Also the importance of thinking strategically and weighing risks.
World of Warcraft taught me that many people are willing to craft items all day, if it earns more in-game gold than actually doing anything fun in the game (actually in hindsight this was true of Eve, and real life for that matter). I sort of... ran an exploitative in-game sweatshop producing things for the in-game markets (e.g. not involving real money or anything that violated the rules of the game).
These two groups of realizations made me pretty good at online games for a little while! My gaming hobby came to an abrupt end when I realized I could just... start a company IRL and be paid non-virtual money.