Based on what we know now there is nothing on the asteroids that isn’t also on Earth in pretty good quantities.
I suppose hoopla is necessary o get anything done but the cold hard fact is that space exploration is basic research - you shouldn’t expect an economic return but may be worth it for it’s own sake.
That is true, on the face of it, but the concentrations are very different. There are asteroids that are solid nickle-iron with a few % of other stuff.
You don't find that kind of ore on earth. Earth mixes stuff up pretty well.
And there has been economic return from space. Billions of dollars worth. Already. Without tapping any minerals.