A billionaire works with a collective to donate money and have a payback clause attached to it. For example,
We'll pay you 8 mil, one and done, and when you get drafted to a 21+ mil, 4-year rookie deal, we get 10 mil back. A billionaire presented with that deal says "where do I send the Loomis truck?"

But even it they can only negotiate getting 7 mil back, then you realize they aren't donating 8 mil, just 1 mil. Plenty of BYU boosters willing to write off a 15% loss for tax purposes. So even if it can't be bankrolled by 1 individual, the are plenty of ways to come up with that money.