Initially Sapkowski gave rights to a different company to make a Witcher game, but it didn't work out and it tanked. After that he was pretty much disillusioned with the game industry and when CDPR begged to make a project of the game he was like, whatever, I'll get my quick cash and bail. He praises the show because they essentially do pay him royalties IMHO. CDPR even gave him some remuneration even though they didn't have to, and used to approach him a lot when the first game was being made for stuff related to the world. He's been nothing but mean to them anyway.