Where do all of these ridiculous tech company evaluations come from?

Is it just me or is there a trend toward baffling tech startups run by hip Millennials which get the most ridiculous evaluations (like $5billion+) but which don't appear to make any money? And then you see their offices in San Francisco and it's all inflatable sofas, ball pools and hammocks, and nobody appears to be doing any work and it's a complete mystery what they do, only that it's something to do with social media or messaging or "leveraging off" some BS trend or other?
 
They remind me of those numbskulls who go on Shark Tank, ask for $250,000 for 5% equity, and then the following conversation ensues:
 
"What are your sales to date?"
"Well in the last 18 months we've sold 20,000"
"Units?"
"Dollars."
"So by what stretch of logic are you valuing yourselves at $5 million?"
"Well you have to realize that <insert dubious reasoning and crazy extrapolations here>...."
 
Am I missing something? Should I get a hammock for the office? 

Just from the photo I'm evaluating this company at $77 trillion