You'll need to provide evidence that downloading actually leads to lower profits before anyone can tackle that question.
The hypothesis that "People who download content buy less because they're getting TV shows for free. If they couldn't download they'd buy instead." might sound fine, there are some problems with it.
* People might be spending 100% of their entertainment budget on TV shows already, so they couldn't buy any more if they stopped downloading. Stopping those downloads would lead to zero additional profit.
* People might be downloading everything regardless of what it is, including a hell of a lot of things they'd never buy (hoarding mentality). Stopping those downloads would lead to zero additional profit.
* People who download might be fanatical about the TV show, downloading shows to watch as early as possible. Stopping those downloads would lead have a negative impact on profit because those are the people who do the grass-roots evangelism that drives hype.
* People download because they believe the content has zero value. Without downloads they'd just watch something else. Stopping those downloads would lead to zero additional profit.
The question of whether downloading actually harms industry or not had not been answered.