Yes Polo should guarantee that you gain back money even if person goes defunct. Have been easy so far.
That is because most of the time money just changes hands on their platform, whoever gambles altcoin trading with the Lenders money and loses you can directly assume that there is someone else who won, which is why you can subtract the amount from their comissions, both for loser and winner and the fee basically pays for the lender instead of borrower.
It indicates that there is risk involved in lending also. What I thought is Poloniex will take care of our money, who doesn't pay us on time.
So it is also time waste for us instead of lending why don't we ourselves go for trading then.