Let us not forget that both gamblers will gamble with what they can afford and based on their income.
That's what it's about, except with the Example you gave, a person who has $10k to bet and didn't have that money, but if he did have it to bet in a casino, I think he would Still spend the Same $100 and not $10k, the difference is that the person with fewer resources would solve his life a lot for at least a few months with that money and would get healthier fun, because $100 won't hurt much if he Loses it , but I'm sure that a Rich person who has $100 to spend Wouldn't know how to gamble.
To me using $100 to gamble is way too big to be considered as what one can risk . Though most people sees as small amount of money but there's certain amount of $100 you may loss and think is a small amount of money, but when it will get to point you will know that the amount of money you considered small turnup to be something huge after calculating the losses