No, I don't delete the primary copy of my photos. I have a NAS for backup and use Carbonite for offsite backup.
Discussion
What if the primary device is a cell phone, same results?
My phone has a removable micro SD card. From time to time, I copy all the photos on my phone's internal storage to the micro SD card, then plug it into my desktop and make another copy there that gets backed up along with everything else. It's kind of clunky.
Hey, it works for you and that is all that matters.
I’m stuck with a predetermined GB size which is why I moved towards a NAS. I’ll rather pay for a NAS, than a third party cloud provider.