Actually I was wondering, what if some beneficiary of current system buys all BTC and destroys his hard drive? Wouldn't it mean that BTC is lost?
They can't currently do that as all the coins have never been made yet, but if someone theoretically did that then yes they would all be destroyed.
Yes, but realise, the more coins he buys, the more they will cost. I dont think anyone would have enough money to buy them all. Every other coin would cost more and more. Maybe though, after long periods of buying/selling, he'd eventually get them all. But there would still remain 2-3 bitcoins out there. And those could always be segregated in many pieces. Their price would skyrocket.