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?
That is a valid point. The same flaw has gold. What if someone buy all gold and destroys it with some acid?
-> keep your hands aways from gold!

you mean with acids like Aqua Regia? yes because that's how you can REALLY destroy elements, with acid!...its not like its part of a processes for gold purification or anything...
Congratulations you've added a misunderstanding of elements to your misunderstanding of bitcoins.