Never going below $0 also prevents them from playing the automatic red balls at the start of each round, which struck me after episode 1 as the obvious solution to keeping the game from ending on a huge downer. IMHO, the tension of wondering whether a team is going to make it out of the red is preferable to "Here's a life-changing sum of free money, but we might take it back from you." Episode 2 ended up feeling like a bait and switch for pretty much that exact reason.