Believe it or not, one of the companies that I'm most worried about is Coinbase.
For example, go look at their employee roster page at the bottom.
https://www.coinbase.com/aboutIn in the past 2 years, I have literally watched that page grow from about 5 employees to what you see now on that page. And they just keep adding more employees. At the rate they are going, unless something drastically changes I don't think that they are going to have a business model that will support all of that headcount and still make a profit.
That's a lot of mouths to feed. It's a natural reaction to assume companies that suck in millions of dollars in funding from fancy people and have lots of bells and whistles actually know what they're doing.
The dotcom thing proved that they often, er, don't. Hopefully lessons have been learnt.
History has proven to repeat itself. Most of the employees there are so young to not have even remembered the dot-com boom/bust, and naively thinking that "this time is different." No it isn't.
I worked as an IT Consultant and developer during the Dot-com years. It was insane, I had more work than I could handle. All of my clients were basically startups being funded by VCs.
One startup client in particular, they had 15 employees (and growing), and had a burn rate of about 10-12$M per year of VC funding for the first two years. After the first 2 years, they had maybe sold their software product (that cost about $100K in licensing) about 8 times. In the third year, the VCs said "Listen, you need to sell your product at least 40 times in the next 12 months, or we cut your next round of funding to a third." That was 5X more than they had sold it for all of the first 24 months!! I knew that was the death knell signal, as the company was no way equipped or capable of that many sales in that short of time. The software had a long sales cycle (about 12-18 months on average), so I knew there was just no way.
Sure enough, I finished up my work for them that third year, and they ran out of funding and closed the doors about 4 months after that. The writing was on the wall.