Have you ever had the battery die in your optical, wireless mouse and not had replacement batteries. Try getting anything done on your computer without a mouse. Pretty impossible eh?
He was even creating epic, future-predicting, keynote presentations, years before you were born. To steal from NPR, who said it best:
In a video from 1968, Engelbart demonstrated the capabilities of not only the mouse but also of the power of networked computing. Titled “A Research Center for Augmenting Human Intellect,” the presentation gained a more informal name over the years: “The Mother of All Demos“
I can only hope that we have more brilliant, passionate people like this in the future of engineering.