Smells like revenue to me.
http://www.adweek.com/news/technology/snapchat-asks-brands-7...
It also doesn't actually mean the company is worth $19B if you say, compare it to a public corporation. There's a huge difference. It's still a highly speculative investment, which is why they're not public. If Snapchat was to go public today, Wall Street would likely eat them alive. This just means that some venture capitalists can be convinced to buy something like 2.5% of the company for something like $475M.
There are enough real companies with real revenue outside of marketing that we can probably safely say this isn't complete repeat of the Dot Com Bubble.
But damn does it rhyme in some parts. Damn does it rhyme.
The late 90s was just insane. Basically you had hundreds of companies much airier than Snapchat, some without even a product. Some of them even went IPO like this. It was crazy. Today looks nothing like that.
If Snapchat is well run, it will use its current ability to raise capital to build or buy other assets that can generate revenue. For a mature company version of this, look at present-day Yahoo-- its core brand is almost dead but it owns a lot of other stuff. If it's not well run (or if the founders don't care) it'll eventually deflate and the latest stage investors will lose big.
The real tragedy imo is that these companies are idolized by the valley hive mind. Smart, young developers seem to be more interested in building social-mobile-ad-generating-app-number-twomillion than work on something worthwhile.
Worthwhile being healthcare, education, space travel, energy, etc. Not some viral app that sells ads.
EDIT: Facebook 2004 to 2009 for a $10B valuation, Snapchat 2011 to 2014 for the same valuation.
Does it matter if its only 3 years old?
All that matters is the TAM and growth rate.