It's a tragedy for reasons MUCH beyond 'unnecessarily lost wealth'. I know you are trying to argue in good faith, but you're flat out wrong in the sense that doomsday despair is EXACTLY what we should all be feeling.
A world depleted of its glaciers, lacking in drinkable water, lacking in animal diversity, lacking in arable land, lacking in coral reefs, coastal cities with all their rich history and culture buried underwater and on, and on, is EXACTLY a hellish nightmare.
Who'd want to live on such a planet? Who'd give a fuck about 290% richer?