Earlier quoted context omitted.
There will inevitably be a downturn. When people say "it's different this time" they don't mean that there can never be a downturn, they mean that when it happens can't be predicted by looking at past events. And they mean that when it happens it will be different--perhaps not as bad. There is a huge difference between this time and last time. The internet is much more mature for one. People depend on web apps now in…
There is a huge difference between this time and last time. Is it, though? Instead of overvalued companies based on the theory of "put it on the internet", we have overvalued companies based on the theory of "put it on the internet and get a billion users". Companies that, by and large, struggle to break even without telling a compelling story for how they'll monetize (let alone achieve or retain) that huge projected…
The companies we're talking about in this discussion, late-stage (Series D and on) startups, already have a large and quickly growing user base. And, yes, most of them have real revenue.
There are, of course, some that don't. Take Snapchat for example. Is it really that difficult to see how Snapchat will monetize?
Everyone worried about whether or not Facebook would ever be able to monetize, but it brought in $4 Billion in revenue last quarter. Last quarter! Twitter isn't growing as quickly as some would like (only 4 million new users per quarter) and has its own share of problems, but it's still on track to bring in ~$2 Billion in revenue this year. It lowered revenue projections for the last quarter of 2015... to $650-710 million.
You mention Uber: Uber's gross revenue is expected to hit a run rate of about $10 billion by the end of next year. Even with Uber only taking 20% (=$2B of that), that's $2 billion in revenue. And they're still growing 300% year over year. That is a holy shit number.
So, yes, there is objectively a big difference between this time and last time.
Could those companies be overvalued? Certainly. Do they need to start bringing in more profit? Yes, but even the most bearish investors admit that takes a lot of time. There may even be a downturn in the market, but it is not going to be 2000 all over again, when every tech company with the exception of a couple vanishes overnight into thin air.