'Passive' investors who dodged BTC, forced to own SPCX which is 3x more volatile

Short-term volatility does not matter to passive, long-term investors.

Also, several mega-cap and high-beta S&P 500 stocks have frequently exhibited higher daily and 90-day realized volatility than Bitcoin.

That doesn't mean that BTC is a better investment (it is not) and it doesn't mean these stocks with high volatility are a terrible investment (they may or may not, but funds of good indices in very strong markets, are).