BLACKWATCH, the essential rule you learn in our occupation (industrial safety) would be that everything we do in life carries some risk. The important thing is how you evaluate that risk and were necessary reduce the danger. In the case of data storage the risk as you correctly state is in the hazard of your data being hacked, stolen, destroyed or you or your organisation being held to ransom for it's return.
The "wanna cry" attacks have demonstrated resoundingly that holding data on local servers or drives makes that data vunerable to such attack and that vunerability is increasing as no persons have been apprehended for that criminal action. Being the fact that those responsible for the attacks have so far escaped with at least several millions (probably many millions) the general belief throughout the IT industry is not if there will be another "wanna cry" but when.
In 2013 my company went over to a full cloud operating system (Google Chrome OS) and moved our data to Google Drive cloud storage. At that time Google stored that data at two data storage base sites in the world which has since been increased to four. In the meantime we have also found that the Microsoft Azure cloud storage system is far better in terms of ease of use therefore we now use that system as main storage, Google drive as backup with little or nothing held within the company itself at any time.
In the above anyone wishing to corrupt or steal our data and also at the same time the data of millions of organisations throughout the world would have to carry out a simultaneous attack on eight very large storage center's worldwide all secured by the latest and very highest technology especially when referring to the Google centre's
The above is not to state that a successful attack can never happen. However, such an attack would have to be highly and extremely well organized (probably at nation state level) and would undoubtedly result in everyone being affected by not being able to access bank accounts etc at minimum and the collapse of distribution systems at worst. Therefore even if a person takes the trouble to each day backup their personal data to drives which they connect and disconnect each time they use their PC, then if there is a successful attack on these cloud storage centre's those persons will still be involved in that with the rest of us.
The above may be by way of the electricity going off. So, while purchasing detachable storage you may wish to also consider the purchase of a portable generator to keep it all going (LOL) Cloud operating systems and cloud storage is the way it is going for all of us, like it or not.
Bill