I like the perspective, but I disagree with your assessment:

In the article Goldman Sachs is stating that cryptocurrencies are worthless

That doesn't appear to be what they're saying. In fact they specifically said that the underlying technology is valuable.

Strongin was more upbeat about the blockchain technology that underlies digital currencies, saying it could help improve financial ledgers.

They did say that most cryptocurrencies could bottom out to zero. This is supported by the data - Every time Bitcoin crashes, every other crypto crashes. If cryptocurrencies were independently valuable, this would not happen, but this shows that their values are not independent. This is not a problem with the technologies themselves. There are a number of different purposes and different technologies behind the various cryptocurrencies, and logically many other coins should be more valuable than Bitcoin.

The issue is that investors are uninformed. There is so much money being blindly thrown around with so little knowledge about the underlying technologies.

We can draw a parallel to the Dot Com bubble. If you had invested in AskJeeves, HotBot and MetaCrawler back in the 90s, you would be sorely disappointed today with your return on investment. Google was not even a player at the time.

I feel like most of today's cryptocurrencies are probably going to be insignificant in the long-term, much like those obsolete search engines. The question is, what coin will become the Google of cryptocurrency?

So far Ethereum looks like the strongest player to me, but that could change very rapidly if new technologies come out that make it obsolete.