Real impact is "low" and the market will reflect that after the hype settles. There wasn't much to pour money into at the start of this tech bubble/cycle so FaceTwitter got a lot more.

Every other business that doesn't aim to be some small boutique has growth and impact in the back of their minds, or got the idea after a taste of success.

And by far the biggest impact in computing has been from NLS-Mother of All Demos and Xerox PARC Smalltalk, who were aiming for exactly that. Measured in the trillions. Each individual startup's hyped up billion dollar share of this pie is small. As it should be, since they handle narrow subsets of functionality and can't even work seamlessly with each other. And most users can't deal with all the different UIs.