No, you are wrong. If BTC fell from $100 to $50, buying BTC still would have been the better investment.
You would buy a BJ for 60 coins, and earn back, lets say, 10 coins. You spent ~$5750 and ended up with $500.
If you had bought BTC, you'd have 60 BTC, and at the end it would be worth $3000. Still the better investment.
Not necessarily. ASIC miner hardware would have been cheaper as a result of bitcoin being cheaper, but not
that much cheaper. The price still has a floor that is controlled by the hardware manufacturing process. So you'd be able to sell a 400ghs miner for let's say $3500 on ebay (as opposed to getting ~ $7000 today).
So buy a miner for 60 BTC, sell it for $3500 and then buy 70 BTC with it.
Of course that wasn't the case, so this is speculation.