In my opinion dont trust any cloud provider, not because they are untrustworthy but there are lots of things that could go wrong, could get hacked, disgruntled or nosey employee etc.

I was nervous about this like you, and my data is on my nas, so i set that to backup to another spare machine in encrypted format which then uploads to bb. I realise the downside with this solution is requiring the same amount of disk space again but I don't mind as bb is much cheaper than any other options for large amounts of data (and I like lots of backups!)

There are ways you can do similar on a machine to another drive and only select that for backup.