Why do the rich get richer?

My mum was telling me that her filthy rich Tai Tai friend just won S$10,000 cash from a supermarket lucky draw. She is always striking lottery or winning some lucky draw even though she is already loaded. Why do the rich get richer? Luck, fate, karma? I have no bloody idea. Think I should focus on the fact that I have food to eat and a roof on my head. *takes a deep breath*