I may have phrased the OP rather poorly, as most people are talking about why they see movies on DVD rather than the cinema. But the reasons for that are kinda obvious. The part that I'm more curious about is the question of why people watch movies that they don't think they're going to like at all? If you don't think you'll like it, why not just skip it both in the cinema *and* on DVD?
You can say "DVDs are cheap / practically free, and I can stop watching it whenever I want, so it's not that much of an investment", but why make any such investment at all if you don't think you're going to like it? Do you have to watch every single movie that comes out? Does this only include new releases, or do you also feel an obligation to go back and watch every movie that was made in the past as well? Is spending time watching mediocre movies really a better use of time than surfing the web, taking a nap, reading a book, going for a walk....?
Am I the only one who's run into this concept of "I've got to watch everything that comes out, or at least everything that comes out that's sufficiently popular", or just the only one who's perplexed by it?
EDIT: In other words, why do I keep seeing comments on the web that go something like "This movie looks bad, I'll wait for the DVD", when one would think that the logic would go "This movie looks bad, I won't watch it at all."