You must differentiate between the types of gambling.  I would say based on empirical data experienced betters in sports wagering and poker can earn a significant amount of bitcoin / money and in fact do every year.  I would argue that specifically poker and sports wagering when done right at the professional level are better than trading stocks because in sports you know so much more about the teams that are playing, the players, their history, the weather, etc. and in poker you have percentage odds and strategies that increase your chances of winning.  At their core, stock trading and sports and poker gambling are all just gambling, but just as the experienced stock trader can win, so too can the experienced sports bettor and poker player.