Although you have a valid point if we look at it from betting perspective but sometimes we bet just to have FUN and not the profits.
I do it sometimes just to see if I win the bet and ignore the odds. In such cases we can bet with extremely small amounts which are obviously affordable to lose.
It's common for many to gamble because they want to have fun, not winning is the main target, but if we have to throw away the satoshi we earn just to have fun without any chance of winning the bet, I will choose to save it more because we don't know what is the value of the satoshi in the future which will certainly be more valuable than today.