This line of Horace struck me as telling for non-celebrity bloggers like myself (there must be thousands of us): contentus paucis lectoribus ("contented with a few readers"; Satire I.10). In the context of this particular satire, Horace is advising writers to be content with a few readers (although Horace was surely proud of his fame).
As, I am sure, it is also true of many others, my motive for writing is self-expression and self-reflection. If others are interested, fine. If not, that is also fine. I do get satisfaction from sharing my reflections because someone else may also find them meaningful and useful. We are social animals, after all. We get satisfaction from encouraging or helping others.
For me, blogging is a sort of intellectual diary that I am willing to share publicly. This drive to share also reflects my passion for teaching and for communicating--I hope--clearly.
And so I am content, as Horace claimed to be content. I am not advancing a particular agenda or a movement. I don't need to stir anyone up or call anyone to arms or make a living from blogging.
(Image of the Roman poet Horace in public domain)