Generally speaking, even if money brings us happiness, it tends to be the kind that money can buy: material things and sensory experiences. And these, we discover, become a source of suffering themselves. As far as actual possessions are concerned, we must admit that they often cause us more, not less, difficulty in life. The car breaks down, we lose our money, our most precious belongings are stolen, our house is damaged by fire. Or we worry about these things happening.
The problem is not materialism as such. Rather it is the underlying assumption that full satisfaction can arise from gratifying the senses alone. Unlike animals whose quest for happiness is restricted to survival and to the immediate gratification of sensory desires, we human beings have the capacity to experience happiness at a deeper level, which, when achieved, can overwhelm unhappy experiences.
From The Pocket Dalai Lama, pages 3-4.