I have a longtime friend who used to play poker for money at high school. He had his bad streaks, but on average, due to being a better poker player than most (mostly as a result of card counting,) he was up pretty consistently, and earned somewhere around $80 per month on average, which strikes me as pretty formidable for a someone gambling with pocket money among high schoolers.
http://www.washingtonpost.com/wp-dyn/content/article/2010/10/01/AR2010100105833_pf.html (one page link; original: http://www.washingtonpost.com/wp-dyn/content/article/2010/10/01/AR2010100105833.html) is a recent Washington Post article on young poker player Steven Silverman. It's interesting.
Even more interesting are his comments and other poker players' comments on Hacker News: http://news.ycombinator.com/item?id=1777385
Some selected comments:
-- jdietrich, http://news.ycombinator.com/item?id=1778364
-- matmaroon, http://news.ycombinator.com/item?id=1778597
-- tsotha, http://news.ycombinator.com/item?id=1778909
-- InfinityX0, http://news.ycombinator.com/item?id=1777624
-- bapadna, http://news.ycombinator.com/item?id=1778094 (included because it is funny)
Wikipedia on 'tilt': http://en.wikipedia.org/wiki/Tilt_%28poker%29
On Isildur1: http://en.wikipedia.org/wiki/Isildur1#Career