If I remember correctly that's a 2.5% house edge, meaning that the casino gets a slight advantage with their odds so that you're basically playing to lose.
If it was 50/50, it would be possible for a lot of people to walk away with more money than they started with. With a house edge, it limits that for a lot of people.
Im puzzling over how they secure the 2.5% house edge, because it will be either hi or lo
Before i choose hi or lo for next roll i have 50% chance at that moment
After i choose say hi, how does my chance of winning increase or decrease