Well, unlike the economy I can’t grow in size rapidly. (And if I did I’d just have another major problem.)
Induced demand and limitless cheap human-quality labor can possibly grow the pie very fast, though even then, you start running into the earth’s finite resources eventually. But it is possible that they are worth much more than $2 trillion long before that.
But that is why I said you can’t just safely assume 15x multiples to continue.