Personally, there are not any sport which you will definitely win bets at. Everything is unpredictable, we can not sure about anything. Just imagine if there is a sport which you can predict the score and the winner before it even starts, you will be the billionaire. All the foretell is to calm down people, to make people believe in their decision. Portugal can win Euro 2016, so why can't Laos win World cup ?
Exactly nowadays we can not predict 100% winning game. In all format of games, we are getting unpredictable results. The most expected players also give very poor performance. So it's tough to predict sports betting. My fav game is cricket and football I know all players performance and team strategy but still I am losing my bets. So I think there is no easiest sport you will find gambling.