Yes you DO need hard evidence, thats how the universe works. Common sense doesnt apply when you grossly over simplifiy the situation and dont understand the full situation. You cant make a common sense judgement if you dont know the facts.
Plenty of things can affect BO gross, piracy after the run is ended isnt one of them. Terrible cam copies that are out of sync and unwatchable isnt one of them.
Download numbers simply dont add up, its that simple. As for why pay? Well the cinema offers an experience you cant get at home, thats why. Whats really hurts tickets? 50 inch TVs and home surround sound, media that is better quality than the cinema, and stupid ticket prices... and crappy movies.