Casino is way more risky for sure. In casino it's all about luck and sometimes RNG, while in sport bets you can predict better who might win now, because you can find statistics about team and players in that team, while best statistic you can find in casino is "lucky" numbers list, which is not helping you at all. Basketball game with 95% chance to win will probably win, while in casino you can't be 100% if you will win