Bets with a positive edge can be found most commonly via sports betting, poker games, and the stock market. Although note that most bets you can find via such methods do not have a positive edge, and the edge is not labelled.
More generally, look for any area where bets can be made, and professionals exist who make their living winning such bets. There are professional poker players and sports gamblers; there are not professional roulette players.
More generally, look for any area where bets can be made, and professionals exist who make their living winning such bets. There are professional poker players and sports gamblers; there are not professional roulette players.