Difficult to borrow money???

The other day, one of my roommates asked us to lend her some money. She hoped each of us can lend her 50RMB. But to my surprise, the others were silent for a while after listening. Then one of them said: OH, I'M POOR AND I DON'T HAVE EXCESS MONEY. Another said: OH, NOW I'M LACKING IN MONEY, SO... Obviously, they refused her politely. I am puzzled. Why do they act like this?? They doubt whether she can give money back or something else??? I suddenly find it is difficult to borrow money from roommates. I wonder whether only close or true friends can lend you money. Is the one who don't lend you money when you are in trouble your true friend??? I THINK MONEY IS REALLY A TEST OF FRIENDSHIP.