This is a very interesting post. Very few people tend to go back and look at their thought process historically like this. Not just evaluating a single action, but a portfolio of ideas and stand them up to the tests of time. So kudo's for doing that.

Of the fifty companies named, 21 are independent, 19 were acquired, four pivoted, and six are dead. I expected more to be dead, outright, but it shows me many companies in search of an out found a willing corporate partner - be it another startup, or a large company, be it Blackberry, LinkedIn, Yahoo! or eBay. Tumblr sold for more than a billion, and Spotify is valued at much more. Others, no doubt, went for nothing except a handshake. Interestingly, none of these 50 were acquired by Google.

This "soft-portfolio" has something like an 80% "success rate"-- if you count success as independent or exited, or 90% if the criterion is "not dead". Normally those would both count as 'successes', but I think you're right to highlight that resume/grade inflation that may make the data less informative than otherwise.