The chick in your avatar, is that you? you don't need to stress your skin by thinking too much sweetheart. let me gamble with a money that I don't have while trading requires you to have money and actually buy and sell to profit, in this case you predict the future price and you'll win if are correct.
This option is good for those with small pockets, they can also cheat easily since it's called "bet on bitcoin price" no hassle to implement a provably fair mechanism.
How are you going to prove that the price was at $xxx in a certain time? you can't but they can show you whatever suits them best and let you to blame the "bitcoin price".