It is very safe, haven't heard anyone complain about it being hacked or losing funds, just that the type of trading on bitmex is risky, another thing is their withdrawal charges, usually higher compared to other exchanges
One of the reasons I really do not fancy trading on bitmex is just simply because right from time, I have always believed that spot trading is usually the best way to go when it comes to approaching trading. I know marginal trading means the possibility of more money, but personally, it is that more money most of the time that has put a lot of people in trouble by losing their funds hugely after getting liquidated. Shit happens in all market, but the thing with margin trading is that, it is a shit that can either make you or mar you as the case may be.
i think it's safe bro. don't be afraid. my brother use that and he said it safe
Being safe in the aspect of security by now is one thing I believe everyone should know that security is something that is on each individual. Bitmex has option for additional security and I believe they have a good secured system in place, which is still what is making them stand strong and growing daily anyway.
We should all must understand is that safety can come in different ways which could ball down on the safety of your funds due the decisions you make yourself. Anyone who wants to start their trade going marginal, should better be ready to learn more and practice spot trading if they have to before going this lane.