I don't know about any other person but personally, I've come to discover that winnings that are unexpected excites the most than the winnings that are expected, regardless of the amount of money involved.
Sure, unexpected wins excites more. There are bets which you will place, you will never believe you will win that kind of bet, so getting a win will be so exciting even if the win is not so much. If I am expecting a win and things end up going my way, then I am not always so happy because I already expected it, but an unexpected win excites me more.
OP, every gambler that is placing his bet on a match is expecting to win and that was ahy he decided to gamble, and it is the same reason that makes gamblers to stake high amount of money because they feel it is a sure bet.
Some gamblers know the risk they are about to take is so high, and they know the chances of them winning are just low, but they will decide to try their luck. When gamblers place bets on games like this, they do it with just little amounts of money because they know the chances of them winning are low. Some people know it will be difficult to win some bet, but they will still place it.