Want to know the difference between dropping out of college and dropping out of high school? Oh, about $5 billion. David Karp couldn't make it through his senior year, but somehow he suckered some venture capitalists into sinking $750,000 in the company he founded, Tumblr. Tumblr is basically Blogger stripped of all its features. It's prettier that way, or something. Vimeo founder Jakob Lodwick uses it to post naked pictures of himself. So do another 100,000 people who actually comb their hair. The venture capitalists valued Tumblr at $3 million before their cash infusion, Silicon Alley Insider reports. Karp, who sold about 25 percent of the company, is now a millionaire on paper. By the numbers, that makes Silicon Alley dropouts only 5,000 times less successful than the Valley's version — right, Zuck?