If your point is that a portfolio of a few "obviously good" stocks is not the sure thing many people think it is, I agree. You can demonstrate this point in many ways. The "top stocks" underperformed. I'm fond of tracking the three stocks named by the authors of Dow 36,000 in 1999. They chose them on the basis of six very reasonable-sounding conservative criteria based on earnings and dividends, willingness of management to invest in the company etc. In 1999 I think almost everyone would have agreed that a portfolio of those three stocks was sure to be fine, and the biggest criticism would have been that they played it too safe. The three were GE, Microsoft, and Tootsie Roll.
If your point is that this is a "trend" that "will continue," that thus you can outperform the market by contrarian investing, specifically by counting on reversion to the mean happening regularly enough and predictably enough that you can beat them market just by excluding (or shorting?) the ten largest, then I doubt it. Basically that would be an idea similar to "Dogs of the Dow' which consisted of systematically investing in the worst-performing stocks of the Dow. The exact details of how to do this kept shifting because each successly tweaked version of Dogs in the Dow failed to outperform, so people kept coming out with new, improved versions.
I found the article itself shallow. Even if you agree that there's a cryptcurrency craze and that it represents bubble psychology, it is outside the stock market, whereas the tech craziness (new economy, it's different, earnings are no longer an appropriate measure, etc.) was right inside the stock market and directly influencing stock market investors. The cryptocurrency craze has cooled off a lot and I dont think it's unreasonable to say that the latest fever has broken (bitcoin hitting $20,000 at the end of 2017, what is it now? $7,000). One might as well say that postings about the Megamillions in Bogleheads are evidence of a stock market bubble.
Annual income twenty pounds, annual expenditure nineteen nineteen and six, result happiness; Annual income twenty pounds, annual expenditure twenty pounds ought and six, result misery.