This is an important observation. There are absolutely angel and venture-backed startups with "real" revenue (fewer with actual earnings), but if you look close

This is an important observation. There are absolutely angel and venture-backed startups with "real" revenue (fewer with actual earnings), but if you look closely, it appears that a non-negligible percentage of them derive a not insignificant portion of their revenues from sales to other angel and venture-backed startups. More broadly, an even larger number of startups are also indirectly dependent on the current landscape, as they operate in regional markets where consumption is being driven in large part by the influx of capital into tech. There's nothing wrong with building a business that takes advantage of these types of situations, but my sense is that a lot of the entrepreneurs running these types of companies aren't consciously aware that they're the beneficiaries of an environment that will eventually change. As such, they're not at all focused on trying to diversify their revenue base and to be frank, it many cases there really isn't an opportunity for them to do so anyway.