Agricultural benefits - After a volcanoic eruption the burning lava can turn into the some of the richest soil in the world. Some early civilizations grew their food (farmed) in the rich volcanic soil.
Energy source benefits - Geothermal energy is a useful way to make electricity. With a ready supply of water and and a steadt source of heat, steam can be created to power turbines which will spin generators to make electricity.
Industrial resource benefits - Volcanoes have sometimes very rich amounts of minerals (such as gold, silver, and copper) deep down under a extinct volcano. We can also make industrial products like road-making materials, cleaning products, and other raw chemical or industrial materials.
Economic benefits - Volcanoes also can bring in tourism. There are many businesses involved in promoting Hawaii Volcano National Park.
Recreational benefits - During some winter days, a person can ski on the slopes of Mauna Kea in the morning (next to the observatories) and surf at the beach in the afternoon. There are many water sports and wonderous hiking trails.
Astronomy - On the island of Hawaii there is a mountain named Mauna Kea (White Mountain), standing 13,796 ft. above sea level. If measured from the sea floor Mauna Kea is the tallest mountain in the world at 32,000 ft. high. It is home to observatories of many nations. Mauna Kea's dry atmosphere is good for infrared study, and it's height ensures clear cloud free nights. The mountain is far away from any crowded city areas so there are no city lights and no pollution in the air for an even better study of the skies.