Figuring out who owns the btc addresses that received the multiple 1000BTC transactions could lay in the small amounts that are also received on those addresses.
These small amounts look like advertisement amounts, so somehow someone found these addresses somewhere.
Questions is where were they found...
For example,
who owns 1FactomGnNFTsTVx8jiGjcLKDpyL65GDsH - looks like a "manufactured" address ".Factom...". This is one of the addresses that transfers 0.0005BTC.