There is no premine on Hive. They would need to buy up 51%+ of all voting tokens. If they did that, we would react as we did with Steem and powerup/vote more. We are close to the "checkmate" scenario of having enough voting that no one entity could get enough to take over the chain. Today they would need help of the exchanges, but with the 1 monthly delay on voting in governance, we would see that attack from a mile away and prevent it. Anything is possible, but the game theory is very tight here, and in practice, we showed what is possible vs. a premine; imagine what we could do without that attack vector.