Something else worth noting: Countless Tumblr blogs have gone on to spawn books, films, albums, brands, and more. We’re thrilled to offer our support as a platform for our creators, and we’d never claim to be entitled to royalties or reimbursement for the success of what you’ve created. It’s your work, and we’re proud to be a part (however small) of what you accomplish.

From Tumblr’s Terms of Service