Why?
Because big things have small beginnings c.f. the universe, earth agglomeration, the sun, galaxies, life, humans, civilisations, businesses, technologies and AI. Everything snowballs - nothing just magically appears from nowhere - it's all just a combination of incremental past states.
People who don't understand how things are made feel as though all we need is more "eureka moments", geniuses, "innovation plans" and "big all encompassing goals" when this is not how innovation works at all.
Innovation is directed evolution of the adjacent possible via the convergence of many secondary composable technologies and ideas and hence is messy, arduous, long and always incremental. Chasing big ideas is like building extremely complex software using the Waterfall method - it just doesn't work too well.
What people should be saying is that we should "reduce the cost of failure", "speed up the iteration cycle" so that a bunch of small trivial composable ideas can quickly be assembled into something extraordinary - like the repurposed cells that create a human, or the combination of engines and wheels that make our cars.
People who chase 'big ideas' miss the DNA for the forests.
You have to work on making DNA before you can build the trees.