I just got news from the bank. The bad news is that I won't get the deal with the parameters which I wanted, so the deal is off. The good news is that I don't have to sell anything in the coming months.
Fuck banks. If mine would've allowed me to borrow against my assets (sitting with them), even for like 1/5 or 1/10 of the value, I would have quite a better stash now. The problem was that my assets weren't their shitty funds (I am NEVER going to subscribe that shit at their conditions, EVER!). There were stocks, but "not enough diversification". There were ETPs (but based on... what's that XBT/BTC thing? No wayyyy this is garbage to borrow against!).
I asked for a bank loan when the interest was very reasonable (and only on the amount actually used), waiting for a low that punctually came and I obviously missed (apart from the measly quasi-DCA I could afford at the time). I could have bought a big sack of corn instead, resold a handful and paid off the interest in just a few months. FUCK BANKS.
You can borrow from yourself in some individual/solo 401k plans (allowable for a single member LLC or a single person proprietorship).
Those are 'magical'- you can tax defer up to 69000-76500/year (!) and borrow up to 50K from yourself (not all brokers support this, but some do).
Talk to your CPA about it.
EDIT: in some solo 401k you can invest directly in bitcoin (in addition to gold, real estate, etc), which makes it really interesting.