This doesn't really directly address the issue of valuations for the unicorns. P/E valuations are probably insane by most metrics - the type of user base growth required to get them in line (P/E wise) with other companies is on the order of double-digit percentages of the global population IIRC. This doesn't really mean there's a "tech bubble", though. It's possible we'll see a massive correction to those companies,…
It's not just a canard that these companies are "not focusing on revenue".