No, I can't, because I don't believe in buying on margin. Why do people do it? I have no idea: they probably don't read through the margin form before signing it, and they don't have a broker that explains the consequences of what they are doing.
People do a lot of stupid things. People take out interest-only mortgages. People get second and third mortgages on their home. People run up horrific credit card bills and live paycheck-to-paycheck.
All of these things are legal. They're just not very wise choices for most people.
It is this lack of knowledge which the manipulators take advantage of. Short selling should be made illegal.