It's much cheaper to build your own than to use cloud storage esecially a secondary storage service like Dropbox. Even blackblaze B2 is $60/TB/year vs you can buy an 8TB HDD on Ebay for ~$200 and if the drive lasts 5 years that works out to be $5/TB/year and adding one or two redudent drives is still much cheaper.
How do you deal with the off-site problem? That's why most people use cloud services -- as an off-site backup that they don't need to manage themselves. Yeah, you could just put everything on an 8TB hard-drive from eBay (not sure that's a great idea for important data) and stick it on a shelf -- but the chance that drive will be alive and not have bit-rotted by the time you need the data is smaller than most people would be comfortable with.
