Yes, but some demos lead to disappointment thus giving the pirates yet another pathetic excuse.
People pirate it to "see if it's worth buying".
Then even if it is they NEVER buy it.
Neo, I haven't had a pirated game since I was ten and I didn't understand the concept of things like copyright. I can't pretend to understand these people.
However, they tend to enjoy illegally downloading a game, claiming they'll pay for it eventually and then never doing so. I can think of one person in particular who does so.