Definitely, it is always risky in fact very risky to leave your coins or tokens in any exchange or online wallet which you don't have access to its private keys, in this case, you aren't really owning those coins and you can lose them anytime for whatever reason (scam, hack..). Use the wallet which you have access to the private keys which is quiet safer.
risk always there will always be how to manage ourselves so as not to impact with those risks, because all the mistakes seem big part is due to our own mistakes not to be careless