Their mentality has to change. Their inner voice that tells them it would be acceptable. First off, the end product might be exactly the same to them when the pirate delivers it. They might not be aware / not care about legal matters, they might not be aware what the EPIC marketplace offers or they might even have had such a bad time on the marketplace that they moved to the pirate service. It’s the service that needs to be optimal from start to end, so that they can get the product more easily, safely, automatically etc. The marketplace service must be fine as well everything from performance to filters to terms and conditions etc. IF people arrive on the marketplace, they must be kept there before they bounce off to check out the pirate service. “Free” is like honey to bees.
They might just be not the person you want as a customer. For someone used to the asset marketplace this will sound odd, but choosing who you want as a connection and customer is very common and rewarding for both sides. I think putting the product online for anyone to buy is risky and not rewarding long term. Some licensing / pricing options that could be displayed have been discussed earlier but you’d still have the product out there to thousands of potential pirates and a large percentage of buyers that are not really (or not at all) your target. My personal preference would be doing business B2B and pick the good connections but that’s me.
Yes they are valid customers, what I mean is that there is a large difference between selling to 20 big companies or 300 hobby developers. When the product is sold the next phases start, including ones that cost money such as support and maintenance. It’s easy to underestimate and hard to control when anyone can hit the buy button. In business with larger companies there is more money to be made for both sides with far less connections to maintain. In most cases, this is just the way to go for sellers. B2C for marketplace assets is not bad, it just looks unrealistic both financially and how much time there will be available for support. Add to that what I mentioned earlier, it’s available to everyone so it can be 20 buyers or 2000 and each can be a pirate.
What I wonder is, how much can we reduce piracy of marketplace assets (source data) if sales are reduced to B2B and customers of choice. It should really be up to you as a seller. If you sell only to businesses of X employees with a certain reputation in your country, good for you 
. I’m thinking out loud here.