Pretty much #1 & 5, or as I see it "Because my parents raised me right."
If I want something and can't afford it, I don't get it. *shrug* Simple as that.
Years ago (well, probably a decade ago), I did play a little morally loose with music. I never got into Napster or any of that, but at work people would have shared folders, and I had probably 3 dozen songs I copied from others. However, I would say the majority of those I would have never listened to if they hadn't been shared. Secondly, after I discovered the iTunes music store, not only did I replace all of the songs I copied from co-workers with legit copies, but my music buying has gone up from a CD a year to probably a couple hundred dollars worth a year. I buy far more music now than I ever have. Because iTunes gives me exactly what I want - cheap, fast access to a huge catalog of individual songs. And as for replacing my pirated songs with legit ones - a buck a song is a bargain weighed against my conscience.
With RPG books, prior to 3.0, TSR had those great CD compilations at a more than reasonable price, so my needs were met. When 3.0 came out, RPGNow became my iTunes. It has an incredible selection at fair prices, and I bought FAR more PDF products than print ones (and I bought A LOT of print products through 3.x.). It is cheap, fast access to the books I want - plus, just like my iTunes collection, it's easy to have at work and home (including PDFs being easer to use without my boss noticing).
Even more, RPGNow helps me try new products I never even would have looked at in the store, and has helped me make far more use of all my products than the physical books collecting dust on my shelves.
So, without the fast, easy access to WotC PDFs, I'm not going to start pirating them - again my parents raised me right. But I will certainly be a less satisfied customer and give more money to the companies that exhibit better customer service (especially given the fact that the number of cool products I want is greater than the money I have to spend on them, so it's easy to make purchases based on my opinion of business decisions).