Indian Creek Island, a man-made enclave near Miami Beach, is Miami's most exclusive neighborhood — not just expensive, but designed to keep nearly everyone else out. The island had a population of just 84 in 2020 and, as Fortune reported, is protected by a guarded bridge and a police force that patrols by land and sea. What's happening? According to Fortune, known as the "Billionaire Bunker," the 300-acre artificial island has become one of the …