I think it is more the desire to have an impact. Seriously as you get older and interact with more and more people you see the choices and opportunities that lead them to the current space-time co-ordinates. And you get a little bit sad sometimes that folks who could have been great have become de-railed due to some addressable issue into crime, or poverty, or drug addiction.

It is hard to sit at a company working really hard to fill jobs and to listen to all the folks who are out of work but not qualified for your jobs. Its hard to listen to the stories of good, decent people who work hard and are certainly capable, unable to break the chains of poverty because they can't both get an education and stay off the streets. Its hard to listen to young people, now young adults, who suddenly realize that it wasn't learning they hated it was the school and now they are trying to make it as adults without a solid foundation.

KA is has three things going for it, the founder is passionate about the cause (so its not going to sell itself suddenly), the technological sub-pieces have finally come into existence across a critical mass, the availability of 'self funded' (which is to say folks who no longer have to work if they don't want to) individuals to volunteer efforts for it.

So being remembered for lifting some fraction of the world (no matter how small) out of poverty by providing educational opportunities, or being remembered as someone who worked at one of the companies that formed the Web as we know it. Easy choice.

I think it's the cause that attracts people. Silicon Valley repeatedly talks about Changing The World and all that people do in the end is to create another web app. Khan Academy gives a lucky few the means to truly change the entire world by working on education, one of the most basic aspects of modern societies.

I wonder if the chance to work for a good cause is a natural filter for exceptional engineers.

When you've already made millions, or when your reputation allows you to get any job you want, money surely becomes a much smaller work incentive.

Or these high profile people really believe in the idea of KA

What they're doing is what carries the charisma.

I get that the cause itself is part of the reason, but there are plenty of opportunities that have great causes that could need help of aforementioned individuals. I really think its Salman Khan, because people believe in him. I can see him being the next leader in SV