Let’s say an online casino has btc as a deposit and withdrawal method.
Assuming A player deposits 1 btc, plays and does neither win nor lose much and then cashes out the balance, which happens to be exactly 1 btc. I am using simple values to focus on the main issue.
However, the btc price was 15% volatile since the deposit was made.
Technically, the player has neither won nor lost based on game play, but he would get a free 15% in value just due to the btc price increase.
The opposite applies if btc loses 15% of value.
Of course it is a nice thing for the casino if the btc price plummets, but potentially disastrous if the price goes up, assuming an average 4% house edge for the casino.
What would be a fair solution for both parties?