Two things: First, I copy my entire body of laptop files to a thumbdrive twice a month. It takes an hour (I've been saving files since 1990) but does not require attendance. I use two thumbdrives, alternate them. If one fails, or my laptop's SSD fails, I'm at worst out two weeks' new files, and I'll just buy a replacement. If two fail, 4 weeks.

15,000 pictures? Suppose each occupies 3 megabytes. That's 45 gigabytes. These thumbdrives will hold 500 gigabytes. And I've not had one fail in the last 10 years.

2. For really, really important stuff, print it out on paper and stash it in a dark, dry place. I think a plastic box in the basement would work. Stick a dessicant pack in there with the paper. You can recover printed text via camera & software. Text on such media has been known to last 2000+ years.