That's the real risk in crypto, just choosing an exchange without considering its security and safety will be risky as it is prone to hackers and frauds. Maybe the owner or the developers might expose the vulnerability of it that results to that kind of worse situation in the mean time.
Cryptopia was well known exchange. You know nothing is perfect, even if you have top tier security there is chance for breach.
'never put your funds on exchange' — if you want to keep your funds safe, this line is enough.