And if it were only about supporting the dev, then yes, buying it from GoG would definitely be the way to go. There are, however, other considerations, such as how much money I want/am able to spend on the product. It's not like buying some bootleg copy off a guy on the street and saying "I bought it so I'm good". If CDP didn't want people buying their games through other channels than GoG they could choose not to sell them elsewhere, and the fact that they didn't shows that they must be okay with people buying it on other services. Sure, it's better for them if people buy it on GoG, but what's best for them is not the only consideration here.