Not sure what you are basing that on, but Binance's security is as good as all the top tier exchanges in this market. In a way you can even say that it is better than the rest in security terms, because they haven't gone through anything seriously damaging yet. Admittedly, Binance is relatively new in the crypto world still, but they as largest exchange face the heaviest stress testing, and they handle everything without many problems.
In more recent terms their security trigger system prevented coin theft as result of an API key attack. In other words, Binance saved plenty of users, and that while these users messed up big time. Even if Binance's security trigger system didn't jump in, the loss of funds would still be people's fault. That's what you get when you use malicious bots and other services requiring input of API keys.