My ebook purchases also skyrocketed after I got a Kindle. But it didn't rise because the kindle made it easy to buy ebooks, or even because I prefer ebooks (for technical stuff, I actually don't). It's because I was reading a lot more. I went from 1 or 2 books a year (if even) to 1 to 2 books a week.

My experience is anecdotal, but it might be worthwhile to ask your acquaintances why they buy so many ebooks after buying a Kindle.