They receive, well, real cash! Cash prizes are fixed cash prizes and/or prizes based on the number of registrants in your event, depending on the laws of your country or state.
For example, a “Winner Takes All” trading competition has a fixed cash price of $1,000. Other fixed cash prize events can award the top 40% of traders a cash prize based on their entry fee. For example, if the entry fee is $10, then the cash prize awarded to winners might be triple the entry fee ($30).
Some cash prizes will increase as more traders enter the event. The more traders in an event, the larger the cash prize!
Next suggested article: How do you determine the winner(s) of trading events?