[rollover]

It turns away more potential customers. The DRM has helped absolutely nothing to protect against copying. The book is already out there on the net as a now "DRM-free" PDF. It's a shame that illegally downloading it is currently the only way to get the format that many customers would be happy to pay for. If I were the author I'd hurry up and quickly put a DRM-free version on a service like Leanpub.

[ricardobeat]

Absolutely. There are even studies [1, plus another recent one I can't find atm] suggesting that piracy can increase overall revenue due to larger exposure.

[1] https://poseidon01.ssrn.com/delivery.php?ID=5550640311191070...