Palantir is relevant because you cannot invest in it. That's the whole point. Did you read the previous part of this discussion about how publicly traded indexes do not represent a targeted bet on the economy because there are plenty of companies that are not a part of them (e.g. Tesla not in the S&P 500) that can completely replace the ones that are?

I agree that betting on publicly traded indices does not represented a targeted bet on the economy. I disagree that bankruptcy is a big risk to index fund investors.