But for the example above: 2^69 / 55,246,870 = 10,684,692,370,060; now take that and multiply by 1.72GB = 18,377,670,876,503GB, double all numbers for 2^70. That's a lot of GBs 
Right, it's 18 ZB, roughly the same as 24 ZB (using 20 bytes per address, i.e. just HASH160, no prefix, checksum or private key).In other words, about twice as much as all the world's storage capacity (HDD, flash, tape, optical) in 2023, and would cost something like $1000 billion1.
1 Using data from IDC and their "Worldwide Global StorageSphere" metric (not to be confused with the "DataSphere", which is the amount created and some 10x bigger).