Here's how he could've doubled his money in 2 minutes (spoilers)

When the contest was announced, my first thought was: "Why don't 2 of them just strike up a deal whereby person #1 invests $5000 in person #2 with the promise of sharing half the returns?"

It's fair, it's honest (at least as honest as investing in a gold mine was), the moderator said they were allowed to pool their resources, and heck if they wanted to make it official they could've gotten a lawyer to draw up the papers the next morning. But essentially, duh, two of them could've walked home with a million dollar estate that night.