Instead, I'm suggesting that you should be interested in (and actively working toward) making money.
Any company needs to decide where their focus should be, Tumblr may well have done the analysis and decided that rather than take their focus away from their core product and focus on monetization (which may only generate a few hundred million in revenue at this stage) it's better for them to focus on their core product now in order to have a chance of monetizing at the billion dollar range in the future.
It's a perfectly rational economic decision.
At what point in their "Humble Beginnings" do you suggest they start thinking about making some money and becoming self-sustaining?
Somewhere along the way they need to focus on being able to provide for themselves. Otherwise it's a giant ponzi scheme where all you get are investors investing in a product that won't return their investment.