As other people have mentionedn the Bithumb hack has nothing to do with Bitcoin itself, Bitcoin is probably the most secure cryptocurrency in the world as it's the one which has been under the most scrutiny from developpers from all around the world, which has been the most intensively tested and which has the more hashing power from large mining operations.

I think nothing is never 100% safe but Bitcoin value would be much lower if there were any doubt about its security.