Instead of investing so much in Hash power, just quarter of that $$$ to buy actual BTC and then you can control the market in much better way.
"quarter of that" = 1/4 * $8 bn = $2 bn @ $6,500/BTC = 300,000+ BTC control the market?
maybe... but wouldn't his buying frenzy willl pump the price? (eating up all sell orders)
then shortly afterwards price crash/correction/dump happens and gets him in a big loss
It's certainly more viable attack, especially if the manipulator don't care about profit/losses or part of government which could create money out of thin air.
Also, if their main goal is to suppress bitcoin adoption/trend, the manipulator could dump the coins anytime when Bitcoin price is increased to kill spirit/motivation of Bitcoiner.