The difference, though, is that the money that Khan Academy has raised is donations. They're not investors who are seeking a (financial) return on their capital. Education is a tough space for startups trying to make money: http://avichal.wordpress.com/2011/10/07/why-education-startu...
Salman had options to go either way, he chose it to be structured differently due to philosophical reasons. There are other folks who are doing pretty well:
http://www.vccircle.com/500/news/niit-sells-element-k-corp-t...