Those people stupid enough to put important data on other people's servers, where the have no control over who sees them and now, after being warned time and time again that this very thing is inevitable, will find themselves devoid of a bank account eventually. At that point, they will:
1) Learn their lesson the hard way.
Calling them stupid is not fair, I think. A majority of the older generation, especially those in their 60s or 70s are only just dipping their toes into using things like smartphones, iPads, emails, a little Facebook, Skype and maybe services like Dbox or Box to "keep their pictures". They did not grow up being exposed to personal computers or smart devices. They also grew up in a time when it was more common to trust authority figures. So now, they are bombarded by ads etc from M$, Apple and Google saying their services are safe- why would they not trust them?
Your comment about "being warned time and time again that this very thing is inevitable" is specious. Certainly, if you are a techie or geek, you would see and take note of these warnings form the tech sites that you visit. The average Joe would not see it, and even if he did would not understand.
You speak as someone who never had to guide an older family member/relative in how to use smart devices.