Putting on my conspiracy robe, I would posit Bitcoin was created by an intelligence agency. You need cryptography smarts and the ability to glue all the various components together aswell as keep it all hush, something an intel agency can do with ease. How else do you uncover vast criminal networks? It was purposefully made to ensnare cyber-criminals. Now as for Monero, I would imagine it has them shaking in their bo…
Also - Satoshi - who? no one knows, really? Dread Pirate Roberts, name insinuates that the role (of site administrator) was handed over to him. There has been speculation that he was not the creator of the site. Tor - created by the Navy.
Why? - Black money / create an "open source", super duper encrypted method of communicating that cannot be broken (unless you control 70% of the exit nodes, whoopsies), get people invested in using it. How many of the dealers that supplied on silkroad where "free-lance" and scooped up later (along with their product and cash)