It’s not quite that simple or all VCs would be in prison. The difference is that some funds to return real money and some companies do IPO and return real money to all the LPs in that fund. In Ponzi Schemes only some of the LPs in a fund make money and others loose all their money. So on a fund by fund by fund basis any individual fund can be Ponzi Scheme - but by definition these are high risk investments that only qualified investors are allowed to participate in. The type of analysis cited in the article is exactly the type of work sophisticated investors do. I suspect that work helped them identify the funds that were the best risk.
Now if you are making the case that Venture Investing as a whole is a Ponzi Scheme, you will have to look at all the public markets and international monetary policy as well. Is it all not a house of cards?