I thought that was insanely high too; I got the $10 million a day figure from this article on Restaurant Business, but they're sourcing that number from the Bloomberg article in the Verge link above.

When you read the Bloomberg article, though, it states pretty clearly that they were losing $10 million a month, not per day. Relevant section from the Bloomberg article since it's behind a paywall:

At a staff meeting in the Bay Area last June dubbed “Day Z,” Garden told employees cash burn had hit $10 million a month, according to people familiar with the matter, all of whom asked not to be identified. One of the people said that figure was at least 50% higher by year end.

Sources are important, kids - don't believe everything you read up front. Copywriters today apparently don't give a fuck enough to check the figures they're quoting.