Oh dear
You do realize I was talking about block generation!
How about something easier for you to understand.
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.
Or someone with a lot of money can amass a huge ASIC farm and 51% BTC.
For sure, a disruption of the BTC network can come in a number of ways, a smart investors doesn't keep all their eggs in one basket, be it BTC, alt-coins, fiat, gold, stocks, houses etc.