Bitcoin is a store of value that will long-term net-increase as true monetary bubbles, like this: http://imgur.com/a/0ZoDu, pop and cause their base currencies to long-term net-decrease.
Something can't be a reliable store of value if it can drop (or increase) 50-100-200% in a day. That is, in the best case, a speculative instrument.
If I had $50m, why wouldn't I invest it in property rather than in Bitcoin?
Gold is prone to bubbles as well. Personally I'm not a gold bug and I don't really see why (in the current day and age) it still acts as a safe haven asset.
Ultimately, it has little economic use, meaning most of its value is just derived from it "being gold". Land, that I get, that makes total sense. You can't make more, and you definitely can't make more land in good locations. But gold -- that seems very artificial to me as well.
But you're right, if I had to a pick, Bitcoin probably makes more sense over gold.