Don't think prize money should be self employment on Schedule C. But for Schedule C,
You pay Self Employment tax (Scheduled SE) on a Net Profit of $400 or more on Schedule C. You pay 15.3% SE tax on 92.35% of your Net Profit (If it is greater than $400). The 15.3% self employed SE Tax is to pay both the employer part and employee part of Social Security and Medicare. So you get social security credit for it when you retire.
You are paying 15.3% for……
SS for employer 6.2%
SS for employee 6.2%
Medicare for employer 1.45% (on all wages & profit, no max)
Medicare for employee 1.45% (on all wages & profit, no max)
