For months it's been discussed ad nauseam that Unicorns are dying. (SquattyPotty might take exception to that!)
I hate to burst your bubble, but I could've told you that was inevitable (and I'm not a professional investor). Putting a billion dollar valuation on a company with no revenue simply because it's started by someone who may have struck oil before is foolish. Investing hundreds of millions into a business void of revenue is similarly foolish. And as they say, a fool and his money are soon parted.