This seems like a smarter move than to sell the Bitcoin for fiat money. If I sell, then I have to pay capital gains tax. When the cash is borrowed, there is no tax. Since I still have the Bitcoin, then I will gain when the price rises. If I only have fiat, the “price” will always go down because of inflation.

There is a small ventilation hole on the top cover with filters, so the HDD can "breath" when the air pressure changes like on higher altitudes but even if there's corrosive fluid leaking into the drive which is highly unlikely, the platters are made of aluminum or ceramics covered with magnetic "dust" which is coated with extra layer of carbon.