OK, no they're not losing money on those events. The contributions there are also money they brought in as part of those events. "Contributions reportable on Schedule B(Form 990) are contributions, grants, bequests, devises, and gifts of money or property, whether or not for charitable purposes."
I'm not tax guy enough to know exactly why they're pulling them out of gross receipts, but they're definitely revenue associated with the events. Most likely some part of every ticket they sell for say the golf outing is listed as a gift or "contribution" rather than just kept as simple gross