There's no difference between miscalculated risk and uncalculated risk because both are considered as risk and could be cause of huge losses.

Some people calculate their risks and when they aren't able to calculate the risks properly then they say miscalculated risk while others avoid calculating their risks and continue taking more and more risks.

We all know that gambling is a risky thing and those who take huge risks with high odds often end up losing the amount they betted.