Well in both cases you have to look at the relative options. I would assume at this point the Tumblr founders have taken some money off the table (though perhap

Well in both cases you have to look at the relative options. I would assume at this point the Tumblr founders have taken some money off the table (though perhaps not) or at least could in another big round of financing. Money has diminishing marginal utility. A few hundred million is a lot of money, but if you've already taken 10 or 20 or 50 off the table, is it life-changing anymore? Tumblr is the sort of success that could probably not be replicated. How many people have founded more than one company that does that well? So I think there's a valid argument that the extra money is not worth the risk of no longer getting to work on such a huge project. I'm sure the founders thought about that. I certainly couldn't criticize them for either decision.