Thats why you should never buy on margin. Wonder how many people got wiped out.
if they don't sell they have not lost anything, the same for those that they didn't sell in 2013 and that held their amount until this pump, they didn't lost anything too, it's a matter how much you can hold seriously, there is nothing more to do, but cashign out at the right time and buy back more coins is something few can do
Im not sure if you know how margin sells. If the margin positions crosses a certain treshhold, your position is automatically closed and you lose all of your money. If the position is a short position, you could end up in debt, even tho I think this is not the case in poloniex, not sure how it works in other exchanges.
Margin can make you rich or can make you broke, thats why it's high risk/high reward.