Buying it has two problems:
- I don't want to spend $15-20 on something I'll see only once.
- I want to see it now. A lot of my movie viewing is spontaneous (e.g., "I'm tired and don't want to do anything tonight... what good movies haven't I seen?"), and I'm not a hardcore enough movie buff to maintain a physical backlog of movies I need to see.
- Reselling is a pain. How? Craigslist? For one thing, I'm not sure what the demand is for random obscure DVDs on it, and secondly, that's more time I burn meeting up with a buyer just to get $5 on a DVD.
I will buy physical copies of things that I truly love and intend to see over and over again (e.g., the Band of Brothers box set, or the Firefly box set...)
More expensive ($10-$20), and I'm already paying for other services to rent movies from. I also haven't bought a movie in years. The large majority of stuff simply isn't good enough to own, and even if it's good I rarely sit down to watch a movie again (if it's on TV, and I have time, and it was good I may watch it again).
I also don't want to deal with physical media at all. And selling it afterwards? So now to watch a movie that is supposedly out at retail I need to buy it (go to the store or wait for it to be delivered), watch it, and then resell it? Add to the fact that many DVDs still have unskippable previews and the entire process is very high on my personal friction scale. All this and I'm in the US. It's even worse if someone is in another country. And people wonder why so many people pirate movies...
There is DRM on DVDs. You used to need DeCSS to play them on Linux http://en.wikipedia.org/wiki/DeCSS