Who said betting on a single match is reliable? As we say that the money you deposited in a casino is highly likely to be lost, so is the money you deposited on sport betting sites, regardless of the odds that you go for. Only what people can say is that parlay is riskier, but it has its own advantages.
No matter how much people try to make gambling to be that easy there is no easy game to gamble on that can guarantee you winning both casinos or sport betting are all difficult and the player is usually the intended loser the moment after making deposits, the odds may be very small and the team that is the favourite to win may be in good form but still the chances of winning will still be slim gamblers shouldn't expect winning all the time because not even a single bet gives you assurance in gambling.