Crypto currencies rely on network transactions to complete transfers. When we are dealing with networks (or anything of value), it is essential the proper security is in place to deter prying eyes.
Any Bitcoin or cryptocurrency wallets where you own the key (physical, mobile, desktop) leave the job of security in your hands. When utilizing third party wallets and services, the safety of your assets are in the hands of that organizations security procedures.
Top developers and engineers work around the clock to ensure the top notch security of cloud services, just don't forget to do your research, it's important.
Cryptocurrencies make you responsible. You need to understand all the proper security and participate in the communities to contribute to changes. Decentralization is crazy. Welcome to the future.