Well, remember that the witnesses control the code; the blockchain itself. Votes for witness are stake weighted too, and this means that anyone with enough money could just buy the accounts from the founders with their mined stakes that are the bulk of the Steem in existence, and just vote in witnesses that would run any code they wanted, and make Steem, Steemit, SMT's, Busy.org - everything that uses the Steem blockchain - theirs.
It's called a Sybil attack, that takes control of the blockchain by having over 50% of the stake, or on other blockchains, nodes, or hash power, and Steem is the simplest to take over.
It would cost money. But not government money. Fakebook could do it. Alphabet (Google) could do it. Amazon could do it. A small cabal of these guys could do it, and hardly feel it.
When you have $10B's, $50M is change.