S&P500 isn’t “the economy” but in the context of talk of a bubble it seems like we’re talking about equities not the whole economy. So let’s just keep taking the short cut …

The top is over performing so concentration is real but it’s not the only growth driver:

https://www.fool.com/research/magnificent-seven-sp-500/

The return / valuation concentration prob not as titillating as the PE run up:

https://finance.yahoo.com/news/surprisingly-excellent-run-st...

True or not true hard to say without better definitions of terms but seems like current profile is not ultra common in history but it’s not a bunch of losers getting diluted out.