Genuine questions here, not rhetorical or trying to imply anything with them.
Why charge more on a DRM free site? Do you think people buying from there are doing so that they can share the book illegally?
If someone wants to share the book illegally, I would imagine they'll just download it from one of the pirate mirrors out there and not bother paying you at all. My guess is you're probably just reducing the number of people willing to pay the price. Classic supply and demand curve against price.
Where possible, I try not to focus on negative motives. Quite simply, if people see a benefit in DRM-free, why not expect them to pay for it? And there are other platforms beside the two I mentioned – it’s not a choice between DRM-free and (for better or for worse) Amazon.
In case your question was not rhetorical: to folks like me, I view DRM as abuse, because it inevitably leads to me paying for something that I won't end up being able to access down the line. It is in direct conflict with building a library. Having the author opt-in to applying DRM to their books (as you have on Amazon and Google Play, for example) and then expected me to pay them extra so I can actually own the thing I paid for makes me take three steps back from the "Buy" button. I tend to just walk out rather than be treated that way. As a result, I've stopped buying Amazon Kindle books entirely (now that I can't strip the DRM). If I'm paying the money, I'm going to demand control, and if I can't get that control, there will be no transaction.
FWIW, LeanPub for your book suggests $25, and the DRM-laden version is $13.50. That's quite the premium!
I reduced Amazon pricing yesterday for Christmas
Makes sense!
This is silly. You aren't competing with amazon you're competing with Anna. If someone is interested in DRM free they aren't stupid. Take the sale but don't take the piss.