http://www.bloomberg.com/news/articles/2016-03-11/instacart-...
Here's the money quote: "[Instacart] said 40% of the company's volume is profitable - meaning most orders still lose money. It also said that it will be profitable globally by summer. However, its calculation for profitability doesn't include the cost of office space, the cost of acquiring shopper workers, or the salaries of its executives, engineers, designers or other employees..."
In other words, a $2b company figured out how to "not lose money" 40% of the time when their lowest paid workers deliver things. Ignoring those pesky cost centers that are developers, designers, hiring managers and executives. When every corner deli within 10 miles of me delivers (often for free) and presumably does so profitably (disclaimer: I live in a major metro area).
Technology has a peculiar ability to light gigantic piles of money on fire. These are strange times we live in.