Why do people keep honeybees for money?

The first part of their name gives a part of the clue. People keep honey bees to produce honey. Bees also perform other useful functions, and some larger scale beekeepers earn money by providing bees to pollinate fruit crops. Without pollination, most of the fruit and vegetable crops (but not grasses and grass grains) we rely on would be 80 to 100% less productive.