"Investigating Factors Influencing Game Piracy in the eSports Settings of South Korea"[0] shows that behavioural intention was the result of social norms and attitude; for example if people who had friends or spouses who viewed piracy favorably they too were more likely to pirate themselves.
People don't pay for content, they pay for convenience. When streaming was still non-existent, and if you weren't a college or high school kid, buying an album on iTunes was less hassle than torrenting it (especially for the non-technically inclined). Now that there's Spotify et al, iTunes sales have massively slumped.
The same goes for games: Steam killed a big chunk of piracy, as having to crack the game and crack again after each update (not to mention no achievements and no official multiplayer) is less of an user experience than just using Steam. However, if as in this case using the Steam version comes with a 40% performance cost... then yeah, piracy gets attractive again.
> The burden of proof lies with the proponents of DRM!
That seems like a just world fallacy. The decision is made based on the perceived risk/reward by the publisher before you the consumer ever have a role to play. If they have internally decided this is "worth it", then it is _to them_.
If you want to correct their internal model of a customer, the one where it is worthwhile to use DRM, then the burden lies on you. Not that I am suggesting you can but, theirs is the incumbent position, yours is the challenger.
If you really don't like the DRM policy, don't pirate the game either. Pirating solves your problem (the DRM) but it doesn't correct their model of you. Lots of active pirates are still seen as fans of the game and potentially customers. They still see an "opportunity to convert" if they can just get stronger DRM out the door for the next title.
Saying "people do pay for content if they can" is seeing it from your perspective. To change their minds you have to see it from their perspective. Even if you feel it is objectively untrue, their perspective is that piracy is lost revenue and DRM reduces that loss.
[0] http://digitalrepository.unm.edu/educ_hess_etds/9/