Many started simply to teach others. The point is that most successful bloggers didn’t get into blogging for money. It’s hard to believe that some multi-million dollar revenue blogs started out as small side projects.
It doesn’t happen overnight. I have interviewed many very successful bloggers and several of them shared that the first couple of years were a lot of work with little reward. Their sites have received few visitors if any during the first few months, but they kept writing and churning out content.