I have data stored in OneDrive. Most of it's not sensitive. I have a Microsoft 365 subscription for our family. Have all of our phones setup to do Camera Roll backups to OneDrive. We never have to remember to back anything up, and in the event that a phone is lost, damaged, or stolen our pictures are always still available on the cloud.
For some people, they don't take the time to backup their data. Having it on a Microsoft server is probably better protected against disasters than having it on their own computers. Microsoft will have this backed up, or at least one would hope they would. But we already know that some people DO NOT backup....so it's probably no worse.
I like being able to get to all of my files easily, no matter what device I am on. Doesn't matter if I am at work, at home, on one of my Mac's, at my dad's house, on my cell phone or my iPad. That's just super convenient.
And as I said in another post here, my sisters house burned down. Having copies of her data in the house didn't help out in this situation.
I get it, some people will never trust having their data somewhere else. I personally am willing to accept that risk in trade for having less worries that I will never lose it and I can get to it no matter where I am.