I put some data in my computer.  My computer happened to be wired such that access to the data immediately flashed the disk usage LED.

My computer is in a room with 5 networked devices with cameras on them.  Corporate AIs are looking through some of the cameras, trying to gather "anonymized" data to later use for training market-guided vision models.

These AIs can read my data from the disk light.

Not only that, anybody that compromises any of those systems, or the servers with access to the cameras, can do so.

By the way, the curtains are open on my windows, and it is nighttime.  The flicker of my disk light is broadcast to anybody who looks at my home.

But I didn't put this data on my computer just to keep it right there for fun.  Oh no, I am going to upload it to the cloud!  Then I can access it from my phone, or my friend's computer, or by inferring it from its impact on what search results and product recommendations I get after uploading it.

The cloud is not a single-user environment.  But it does make it a little harder for thugs to destroy your evidence, to upload it to a cloud.