I started self-publishing in 2011. I've made a little bit of money; nothing approaching minimum wage. But I've also had hiatuses and sabbaticals in the last five years. Still and all, I've had a lot of downloads. Especially free downloads.
Across all channels, I've given away roughly 100,000 ebooks since 2011.
Inarguably, this has resulted in a fair few people finding my work, and going on to purchasing other ebooks I've written.
I'll be generous and say I've had about a 5% conversion rate. Which is actually pretty terrible, if you ask me. I've though long and hard about why the conversion rate is so atrocious. The first and most obvious possible reason is that my writing is godawful. But my ratings simply don't bear that out. Sure, there are those who don't find it their cup of tea; you can't please everyone. But I maintain a consistently good to great average everywhere my books are available, and on Goodreads.
No, I've come to the conclusion that readers interested in free books are primarily interested in the free part, rather than the book part, and when 'free' is replaced with another word, like '$2.99', they quickly lose interest.
So. Starting today, I'll be charging for my work, barring the Comes the Conqueror serial and the works I have on Wattpad.
I've given free five year's worth of a fair shake. Now let's see how paid treats me :)