Why do you think Naples is so densely populated, despite the obvious threat from the volcano Vesuvius?

Explanation:

Volcano acts as a main source of Naples. Pompeii, a big honeypot site attracts numerous tourists that requires hotels and restaurants which results in huge income from tourists.

The houses closer to the crater provides better sight across the entire Bay being the most probably danger area.

The land here is fertile and is best for greenhouses and farms. Local tomatoes, citrus fruit, grapes are produced in this region. The locals don't worry about the danger of the deep red area.

The important of volcano is the area’s topography, economy and is instrumental to its culture.