Both. My wife and I are hobbyist photogs. Majority of her photos on with a phone but we both have DSLR cameras that we use often for kids, family, vacation, and other photography opportunities.
The 100k photo could be an exaggeration but then again, it might not. I need to look into that. I have 40k of photos myself and my wife takes far more than me, so I estimated.
We have enough storage at the moment that Google Photos and iCloud are essentially acting as redundant cloud storage. They both have enough capacity to house all of them equally (we pay for it though since we both have accounts). So this project isn't a necessity so much as me wanting a more organized and physical place for the photos.
I really wish I had the forward thinking to do this 10+ years ago because using a physical ext hd for my main backup and then linking the cloud storage to that drive would've made this a whole lot easier. Instead, I'm basically retro fitting it. My brain isn't tech savvy enough to work through the process of loading all of the cloud photos onto the hard drive AND moving forward, continue backing up any new ones w/o creating a ton of duplicates, etc. (I've already committed this issue once before and somehow ended up with random duplicates...not even sure how it happened).
End goal: Photos are backed up, organized, and when kids are older and out on their own, it's easy to share these with them and others who may want access. Gone are the days of handing down photo albums and tote bins full. Worst case, I filter these into "professional versus snap shots," keep the best ones, and buy photo books (I've done this before and it's pretty easy, fun....just takes up space)