The reality is that there are anti-BTC entities. There are also big miners. At the right price, big miners may sell their mining hardware to anti-btc entities.
You had mentioned an entity that owns lots of mining hardware. I agree that is a problem.
Suppose there are multiple such entities now, BTC will be in trouble.
You can read about it here: http://en.wikipedia.org/wiki/History_of_Bitcoin
"the vulnerability was exploited; over 184 billion bitcoins were generated in a transaction"
"Within hours, the transaction was spotted and erased from the transaction log after the bug was fixed and the network forked"
Here is something I found amusing, there was even a time when anyone could spend other peoples coins.
https://bitcointalksearch.org/topic/m.1620493
"When Bitcoin was first released, it contained two completely fatal bugs that made the entire system worthless."
"The first bug was that scripts were concatenated before being run instead of just using a shared stack. This meant that anyone could write a scriptSig that always evaluated to true and claim anyone elses coins."
So as you can see, when there is a critical attack or a fatal bug, all that happens is the network adapts, things get fixed.
There is no 'panic among BTC users'. No 'drastic price drops'. Most people would not even know anything happened. Did you know about the things I just mentioned? Didn't think so!
You cannot 'destroy Bitcoin' (as you put it). Bitcoin is an idea.
Now I have completely 'proved you wrong' on every point