The difference with computers in the "cloud" is that there is a much higher incentive to hack them since there is much more data on them, and hackers can be fairly confident that they will get valuable data in a hack. This is not the case with your personal computer. So if you are bad at security, I would argue that it is much safer (from a security point of view, at least) to store things on your own computer, since your mistakes are much less likely to be noticed.