What You Can and Can't Learn from Games
Competitive games can be one of the best areas for training certain types of skills. However, they also have some limitations and distinct weaknesses that are worth noting. This sequence will aim to demonstrate some of those strengths and weaknesses, using both theoretical arguments and practical examples/case studies.
I have been world #1 by Elo rating in multiple games (insofar as this was being tracked), won major tournaments online and in person, organized competitive events, written articles that have significantly advanced the community's understanding of some of the games I play, etc. I say this not merely to boast but rather to point out that I have some experience in high level competition (though I've never been a professional poker player or similar). Most of the games that I am best at are turn-based strategy games of one sort or another (generally card or miniatures games), though I dabble a bit in other genres. 
In general, I think games can be a great way to train certain aspects of one's mental skills, especially in the realm of strategy and practice. However, I also feel that they have some distinct weaknesses that can limit them as a training ground. This sequence will go into more detail on how I think that shakes out in actual practice, as well as describing some recommendations as to how one might use this.