Mea culpa for what? For greedy traders* not understanding the risks of margin trading?

( *) I'm playing with small money on poloniex as a greedy trader. I made +400% in 3 months, but I don't expect to be refunded if I lose everything for a mistake I made. I would only hope for a refund in case of a bug-related issue.

Losing your entire account is not a normal risk of margin trading. They were way too quick on the margin calls.

Depends - if you go long on X and your collateral is all (or mostly) X, then it's a normal risk to lose everything.