I met a traveller from an antique land,
Who said—“Two vast and trunkless legs of stone
Stand in the desert. . . . Near them, on the sand,
Half sunk a shattered visage lies, whose frown,
And wrinkled lip, and sneer of cold command,
Tell that its sculptor well those passions read
Which yet survive, stamped on these lifeless things,
The hand that mocked them, and the heart that fed;
And on the pedestal, these words appear:
My name is Ozymandias, King of Kings;
Look on my Works, ye Mighty, and despair!
Nothing beside remains. Round the decay
Of that colossal Wreck, boundless and bare
The lone and level sands stretch far away.”
By which math? 90% of the world doesn't know 90% of the history and doesn't care to know. The same history that includes big names of their era. Steve Jobs may be held up as an Ozymandias of our day, but will he be remembered for any of his "accomplishments" a thousand years from know? I doubt it. Why? How many Steve Jobs does 90% of our planet remember from 1000 years ago? One, two, ten, Zero? So is it about a named legacy or an anonymous one? If you are talking about impact. Sure. How about your impact on those whose actions affect your life the most? Whose choices influence your decisions about your life? Why does the focus have to be binary? Either, or?
I feel 'leaving a legacy' would be dying knowing that your work left some tangible mark on humanity that you shared the planet with. It doesn't have to change people lives twenty years from now. Just the fact that my creations were enjoyed by hundreds of thousands of people in an year(or five years) is the satisfaction most people would happily die with and would include in 'legacy'. Of course there is a different spectrum of 'legacy' for different profession and depending on your work the value of 'legacy' would fall somewhere in the spectrum specific to your work. So comparing 'legacy' across professions might not even make sense as long as you are helping thousands(or some higher number) of people. And as others have said, I believe 'impact' is a better word for hacker/scientific community than legacy.
For there will come a day when even Jesus, Shakespeare, and Newton will be forgotten. Eventually, we will all be forgotten.