Crap, just between the main drives on computers in my house I easily have 20-30tB of raw disk space.
It might be a lot to transfer...yeah. At 50Mbps that's what...a month of sustained transfer? But how valuable is your data?
1 - https://www.newegg.com/Product/Product.aspx?Item=N82E1682217...
UHD Movies? Why would you save those in the age of streaming? Family pictures/videos? At 20TB, you must have hundreds of thousands of pictures. There's not enough time in your life to look at all those! The only thing I can think of is that you shoot photo/video professionally, or maybe do some kind of 3D/video rendering?
But I agree with you - when you have this much data, why the hell are you transferring it to the cloud? Buy a couple harddrives, load them up, and stick them in a safe.
Heck, my parents have >10tB of raw storage between their home and work computers. Even though they aren't data hoarders, between software, important documents and email and videos and pictures of grandkids and friends they probably easily sit at 4 or 5 tB of total storage that deserves backup.