Well, as long as things are going smoothly, what's there to complain? But if the AI bubble bursts, this can have a catastrophic effect on the entire market. Those 7 companies, which effectively comprise 1/3 of the index, will drag down the entire economy down the drain.
And to see such a small number of companies wielding so much power over the market is unheard of. Not even during the heyday of the Nasdaq bubble was there so much concentration in just a few stocks. If we don't do anything, it's only a matter of time before this blows up in everyone's face.