It's an irrelevant point because ETFs incorporate more than just US stocks. You have global stocks (tens of thousands), options (a million expirations), bonds (3 million cusips) , crypto, futures, and the list goes on. And it becomes a combinatorial exercise... The article is pointing out the lack of publicly listed companies in the USA. But we also have private stock in ETFs now. And not to mention a handful of bloc…
I hope to god "investors" don't fall for the "blockbuster" IPO of SPCX. Remember in 2008 when Standard and Poors was giving AAA ratings to junk CDOs at the investment banks behest? SPCX isn't going to collapse the global financial markets, but the exact same shady rules changes and suspect IPO structure reeks of banks trying to pull the wool over retail's eyes.
SPCX is maybe $1.25tr now - and he has a similar equity milestone deal to just 5x to $7.5tr. Its a big number. For comparison, NVDA is already $5.2tr+
So my guess is people will assume any investment in SPCX will be a 5x return in a short period of time.
Also a company this large will get swept into many indexes, including the S&P500 - so most investors will own it by default.