Not because they existed for so long they will not scam, just like cryptopia, they existed for a long time, but the outcome of their business is bad, they go bankrupt and I guess there are users who were not able to withdraw their coins and that's scammy.

You really can't trust them, therefore you should not only trust one exchange, that is to minimize the risk.
Thus far, Hibtc is still a decent to me, that's based on my own experience only.