There was, once upon a time, some limit to the market valuation of a company that approximated the most money they could earn if they came to dominate their entire market, times the inverse of the rate of return for highly secure (like AAA) bonds.
Now speculation assumes that companies will grow to exceed the size of their whole industry, perhaps in the near future, and returns from highly secure investments were really low post covid (resulting in pretty much a 40x valuation multiplier), which has just... held on since then.
It's weird, and I don't like it. Why should a company ever be worth more than all the money it could ever make?