Then why do people sometimes practise such things and believe in them?
 
Because of greed, fear and ignorance. As soon as people understand the Buddha’s teachings, they realise that a pure heart can protect them much better than bits of paper, bits of metal and a few chanted words and they no longer rely on such things. In the teachings of the Buddha, it is honesty, kindness, understanding, patience, forgiveness, generosity, loyalty and other good qualities that truly protect you and give you true prosperity.