When we say it is decentralized, it means no one is in control of it. It may sound dangerous since we are used to being control, but actually for the first time, we would like to bring change. We should not let our government control us all the time.
Decentralization is not dangerous if it is implemented correctly to use Proof of Work (PoS) and a reasonable number of confirmations... instead, it is more secure.
It is however dangerous if you are unlocking your funds in an un-safe environment (mobile device, vulnerable OS or compromised malicious application that will log your passphrase and steal your funds).