Hey tzm, wanted to contact you about something. Could you drop me a line at my e-mail (zaki.rahaman@gmail.com)
I suspect the main reason is the obvious one: such startups are extremely rare, and there have been only a few hundred or few thousand seed-funded startups. If you compulsively read Techcrunch or HN you'll get a skewed view of the startup world and conclude that such exits are much, much more common than they really are. The vast majority get acquired for $10M or less.