Seattle,
The main reason I would say that may not prove out is index weighting. In a bad market the index funds get sold and the largest weightings get punished more. If the after market high of $1,654 holds to the Friday close AMZN will represent 3% of the index. Also, history shows the most overvalued as well as cyclical stocks face greatest principal decline. Consider it a last man standing. I doubt that the S&P 500 will fall without the 14% index weighting to Apple, Microsoft, Amazon, Alphabet and Facebook taking the brunt of the hit.
Hey you are right for now. Hope it works well for you.
On another note received my mid-cycle chemo CT scan. All tumors reduced greater than 50% in linear dimension. So think of it as a deflated balloon with significantly more reduction in tumor burden. That is good news for someone my age, and it looks promising but still hurdles ahead.
Igy