Why didn't people of New Orleans expect that in some days 80% of the city would be underwater? What went wrong that time?

Several factors contributed to the failure to anticipate the extent of the flooding in New Orleans:

• Underestimation of the Storm's Strength: While warnings were issued, many people did not fully grasp the potential devastation of a Category 5 hurricane.
• Levee Failures: The levees and floodwalls designed to protect the city failed in multiple locations, leading to widespread flooding.
• Complacency: Some residents may have become complacent due to previous storms that did not cause as much damage.
• Communication Issues: There were communication breakdowns that hindered the dissemination of accurate information and warnings.