It no so much that, but more of a control aspect. Once my backups are on someone-elses-computer I've lost control of them, and knowing my luck the day I need them will be the day the cloud provider has an outage, or even worse, goes offline.

There is no way the big cloud providers, AWS, GCP, Azure go offline without a notice period (even medium size one like DO).

Use a solution that you can easily switch from one provider to another one, switch when there is any warning that the one you use might be in trouble. In the same line, make sure people in your family (or technically savvy friends) understand your system, are able to switch and know to pay the could provider bills if you're not around - unless it is ok for your entire storage to disappear when you die of course.