There is a well-worn joke in the economics profession that involves two economists – one young and one old – walking down the street together. The young economist looks down and sees a $20 bill on the street and says, “Hey, look, a twenty-dollar bill!” Without even looking, his older and wiser colleague replies, “Nonsense. If there had been a twenty-dollar bill lying on the street, someone would have already picked it up by now.” (from [0], but many retellings can be found on the Web)

I think you are right that Slava has exaggerated the truth in order to make his point -- as economists often do when talking about the efficiency of markets. Any engineer knows that nothing is perfectly efficient; yet markets do tend to be very efficient, and get more efficient the more money flows through them, and that fact deserves respect and consideration.

And what Slava is saying is something I've definitely observed over the years: a lot of successful businesses are created when changes in the environment open up new opportunities. Sometimes it takes a few tries before someone figures out the right formula -- there were several search engines around before Google appeared, for example, but they're mostly long-forgotten -- but whenever a major opportunity opens up, sooner or later a business will find a way to address it.

So I think paying attention to shifts in both technology and consumer behavior can be valuable for would-be entrepreneurs.

[0] https://financingefficiency.wordpress.com/2011/10/19/the-20-...