Other investments require even greater leaps of faith. You can do a lot worse than Bitcoin. : Bitcoin enthusiasts are in the middle of an existential crisis. Since its mid-April high, the price of Bitcoin has tumbled by as much as 47%. Meanwhile, China — where up to three-quarters of the world’s supply comes from — is curtailing mining and trading. And how solid a rock is the world’s largest cryptocurrency when a few cryptic tweets from Tesla Inc. founder Elon Musk can send it wobbling? Institutional investors have been heading for the exit — for gold.