A negative progression betting strategy in blackjack involves increasing bets after each loss, with the aim of recovering losses when a win occurs. While this approach may seem like it could eventually balance out losses, it comes with significant risks. The main implication is that during a prolonged losing streak, bet sizes can escalate rapidly, leading to a depleted bankroll or hitting table limits before recovering. This can result in larger losses than initially planned, making the strategy risky and potentially unsustainable over time.