As of 2015 YouTube reportedly hadn't turned a profit but was breaking even [1, 2]. If the world's number 2 website's business model wasn't turning profits after 9 years... we can probably expect the same for snap.
Definitely makes you wonder about the viability of the ad revenue model.
It's an evolving market. TV / apps / video are all converging. You can look at the first 10 years of YouTube as customer acquisition. It's a long game. Snap is likely similar as is twitter. This realtime private zeitgeist.
[1] https://www.wsj.com/articles/viewers-dont-add-up-to-profit-f... [2] http://www.businessinsider.com/youtube-still-doesnt-make-goo...