At least with sports betting skill can make money. Just betting on the first place team to win over the last place team for example, it won't always win, but typically will. Of course bookies know this and so the payoff isn't enough to make a living on (if you can figure out the exception and bet only on the last place teams that win you can live well). Statistics are generally well studied in sports, but if you study how a team is coached you can find cases where they have a better than statistical chance to win a game they are expected to lose. Most people betting sports either always bet for their team, or bet on statistics, so if you can exploit something else.