Why all the people left hashima island in JAPAN ?🤔

For many centuries, people living on Takashima -- a big island not far from Hashima, gathered coal, which lay close to surface.
In 18-19th centuries Takashima island was part of the feudal lands belonging to the Fukahori family. They saw the profit that coal mining started to bring and took control of all bargains in their own hands.
Takashima coal had high quality and soon filled the treasury of the Nagasaki with foreign currency.

At the end of the 19th century they sold the island to Mitsubishi, which was a shipping enterprise then. The new owner built dwelling houses for the workers.
Hashima produced about 150.000 tons of the coal each year, and its population in 1916 was 3000 people.
In 1959 the population of Hashima was over 5,200. The total square of island is 6.3 ha, and 60% of it are rocky slopes where most of the dwelling houses are built.Between residential houses, there were squeezed a primary school, a secondary school, a playground, a gym, a cinema, bars, restaurants, 25 different stores, and a Buddhist church.

Hashima citizens had no umbrellas, as the mazes of corridors and stairs connected all dwelling houses and served as a transport system.
Housing, electricity and water were free for workers, but all residents had to take part in public works and clean-up of the territory.
The most remarkable trait of this place was a total absence of the ground and plants. Hashima was nothing more but coal ash, laid around bare rock.
At the end of the 1960's Japanese economy skyrocketed, and coal was admitted an ecologically dirty fuel.
The government started shutting down coalmines around the country, and Hashima wasn’t an exclusion.
Mitsubishi reduced staff on the Hashima, retrained workers and sent them to other subsidiaries.
By 1974 there were about 2000 people left on the island, and on January 15, 1974 the company officially announced the closure of mine.

Hashima now is an abandoned and forgotten island, which looks as a strange lighthouse guarding the entrance to the Nagasaki bay.
In September 2008 Hashima (Gunkanjima) island was included in the list to get the status of UNESCO world heritage as a monument to a whole period of the Japanese history.