When something needs to be done in the world to rectify the wrongs, if one is really concerned with benefiting others, one needs to be engaged, involved. This is action out of compassion.
Material objects give rise to physical happiness, while spiritual development gives rise to mental happiness. Since we experience both physical and mental happiness, we need both material and spiritual development. This is why, for our own good and that of society we need to balance material progress with inner development.