If we consider outside of the language of gambling then this is a big amount and the person was not right to bet with such amount. But if we describe it in gambling terms then it is very simple because win or loss is a common aspects of gambling. Although large amount of money is used in this bet. However, in gambling bettors participate in betting with having the risk. A gambler who placed such a large bet against such small odds he may thought would win or he took a risk. Usually losses by the odds of 1.01 is comparatively less. But it's nothing but bad luck and he had to lose from that particular bet.
Any bet that has that kind of odds is almost a sure thing, however if he was the kind of gambler that liked to make bets on those kind of outcomes with a very high probability of happening then it was just a matter of time until they found themselves in a situation in which they lost their bet as something completely unexpected happened during the game, so it would not surprise me if this huge bet was in fact the whole gambling capital this person had at the time and lost everything in a matter of minutes.