Say someone invents a new super ASIC that's thousands of times faster then the best ones currently on offer. They set up a farm, grab 99% of the net hash rate, attack the block chain a bit, let the difficulty rise to a hundred times higher than it was, then switch the farm off. Bitcoin is stuck at a crazy high diff and effectively ruined, transactions grind to a halt, game over.
So someone has the ability to make hundreds of millions of dollars by obsoleting all other ASIC technology overnight. They could make the hundreds of millions of dollars by mining coins themselves or they could make it by selling next gen tech to miners. Instead they spend millions of dollars to develop the tech, build out a massive farm and then lose all the money by ruining the technology and coin.
Yeah that seems likely.