He lost money perhaps twice. First, he wasted an endorsement for $30 million in worthless paper. Next, he may have to pay taxes on that $30 million because that was the value at the time. But the next year, he can endorse something else and write off the loss.
Maybe though, he could argue the $30 million was fraudulent and never received, so he can avoid the taxable income.
He can write off his losses completely over time. Your tax laws allow you to siphon your losses over time until they’ve been completely absorbed.