The meme stocks can easily be pushed around regardless of what the broader market is doing ..... AMC at $50 and GME at $300 still have market caps of just $20 Billion each .... that's tiny compared to the $1+ Trillion market caps of APPL and other mega caps ....
When GME ran up from $20 to $500 in January and then quickly dropped back to $50, that was NOT a reflection of the broader market, it was strictly a trading frenzy in an individual stock that had a sufficiently small market cap that allowed it to pushed around by the Reddit crowd and hedge funds than played alongside.
The S&P500 doesn't reflect the action in the meme stocks .... yes, S&P PE's are somewhat elevated, but hardly extreme, imho.
The S&P500 is up 11% YTD, a very good year so far, but hardly frothy.