Piracy may the opposite effect for software but it definitely has a negative effect on entertainment related IP.
High school events where I grew up were basically an iMac with the student body officers' MP3 collections and a PA system. All the pirated MP3s people were playing at those various official and unofficial gatherings of my youth led to me buying CDs once I had money of my own.
Has a non-industry-affiliated research group produced causal data (not just declining sales figures) showing that noncommercial entertainment piracy is a net harm?
If you read the fine print in that study, it is concluding the cost of the piracy purely in terms of 1 download = 0.2 lost sale. There's not even a discussion of the potential word-of-mouth effects or later sale generation potentials for pirated music.
What if they lied about how much music was worth though? You can stream 10,000+ songs in one month for the price of one album today, in the early 2000s we were asked to believe that was $10,000+ worth of music and their suffering was relative to that...
The Institute for Policy Innovation (IPI) is a think tank based in Irving, Texas and founded in 1987 by Congressman Dick Armey to "research, develop and promote innovative and non-partisan solutions to today's public policy problems."[1]
IPI is an associate member of the State Policy Network (SPN), a network of right-wing "think tanks" and other non profits spanning 49 states, D.C., and Puerto Rico.[2]
The conservative Capital Research Center ranked IPI as amongst the most conservative groups in the US, scoring it as an "eight" on a scale of one to eight.[3] IPI has received funding from corporations like Exxon Mobil and organizations like the Kochs' Claude R. Lambe Foundation, Scaife Foundations, the Bradley Foundation and others....
But it's well-documented that piracy negatively affects music, film, and game studio income. See, e.g., https://www.ipi.org/ipi_issues/detail/the-true-cost-of-sound...
Piracy may the opposite effect for software but it definitely has a negative effect on entertainment related IP.