Opposite attracts- it is true for living creatures. You will find, daughters are more attached to their father and boys are attached to their mother. You will all notice that the atmosphere of a hall full of guys will suddenly change when a girl enters the hall. It is the chemistry or the chemical composition of living creatures which is so intelligently made by god, which helps creatures in maintaining the reproduction cycle.
Now a step further: a man who always maintains a tough posture in his initial stages of life, gradually mellows down. In other words, a man who grows older, adopts the posture of a woman. The other side of the story: A woman, who in her formative years till about middle age is regarded as emotional and generous, turns tougher later, like a man. I have even seen some bearded women. So it is all a ball game of opposite attracts.
Now coming to a materialistic life: you always find a man with more money, has a desire to earn more. A man with moderate savings is more generous compared to a rich man. I am sure many will not agree with this statement, but this is the fact of the life. Money attracts money. The more you earn, the desire to earn more will increase. A contended man will always find solace in what he has; compared to a greedy man who will spend his whole life in earning and grabbing things of others.