You make a good point, but that still doesn't explain everything. If they're just bandwagoners why wouldn't they also buy the comics?
I don't think continuity can be the issue either thanks to the internet. It also helps that most trades at least have like a brief recap or summary explaining the character and how they got where they are in the story. don't the single issues do that too? If they don't it's kind of stupid.
This whole thing seems kind of snobbish to me. It's kind of like this: "Yeah, I can't wait to see Avengers 2!! I'm going to the midnight premier and everything!! What's that? You read the comics? You're such a nerd."
Investment cost. It would take time, money and effort, something they do not have a wish to spend. All they want is to seem hip and cool at that moment and well..
Trust me, years of reading folks on forums bitching about the continuities. Again, investment costs are too high for them. They want a fast satisfaction.
It is, and so are they. They are always in large numbers and the most shallow pile of shit you will encounter. They were the kids in high school that described themselves as the "cool" kids and would judge others. Basically you live the life they think it should be, then you're cool... unless they call you a poseur. They're shit, just ignore them.
Another story, back in the late 80/early 90s, I used to wear comic t-shirts out in public during the summer. Amazing the number of folks that would chase after me asking where I got the Ghost Rider shirts, Grimjack and Grendel ones. Hell, my ex took my old Grendel shirts... bitch.