This company is a disaster. They are even too stupid to understand the concept of account deletion. "How to delete your Gumroad account: From your Advanced Settings page, scroll to the bottom of the page, then click Delete your Gumroad account? After you've deleted your account, if you try to log back in, Gumroad will make your account "live" once again. Therefore, if you really want to delete your account, click Delete your Gumroad account? and don't log in again. Just... just go." WTF? That's not DELETION, that's SCAM and a GDPR violation. https://help.gumroad.com/article/37-how-to-delete-your-gumro...
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.
They don't protect anything. Probably 90% of your catalog is out there on the net and findable with a bit of googling. In the end it's just a bad business decision. You scare away potential customers and your stuff gets pirated anyway. You're degrading your own product and artificially creating a situation where the pirated product is actually a better one (one without a watermark) than the one you are legally selling. You've got to realize how insane that is.
A digital watermark is automatically inserted customer information into a purchased product to restrict it's usage only to the buyer of that product. To me that's exactly like Digital Rights (Restrictions) Management. Calling something that contains digital watermarks DRM-free is deceptive to the customer. But long story short, if it contains watermarks I don't buy it.