Just because both of them have high correlation, that doesn't mean Bitcoin price isn't affected by S&P 500 price. It's more likely both of them affected by global event 
For years people in this community were telling that Bitcoin is new gold, that it's a hedge against wars, economic crashes and all the other disasters, and people really liked to post negative world news, implying that it's bullish for Bitcoin. Covid-19 crisis was the first real test for Bitcoin, and by some marks Bitcoin failed it - it crashed together with stocks and other markets, showing that it doesn't have these hedge properties. This is the real problem here, at least to people who justified their hodling with those ideas.
that still remains an isolated incident whereas there have been other cases of other markets crashing while bitcoin not giving a shit about any of it all. nowadays it is being exaggerated in the media for FUD purposes.
additionally if you check bitcoin behavior with other markets you can clearly see that the drop that bitcoin had was a normal size drop that is also very common in bitcoin world. meanwhile the drops that other markets had were catastrophic by their standard and extremely rare. adding the fact that bitcoin recovered as soon as the panic sell (because other markets were dumping and FUD was at its peak) ended you can see bitcoin outperformed everything else.