Donationware rises and falls with the level of commitment people have to the product.
If I were to get your book from someone I know, or stumbled upon it, or something, I would have no emotional attachment to it whatsoever, initially. After reading it, I might like it, or not.
Now, if you were to give it away for free to all MobileRead members, me being one of them, I would feel like you are my friend. And I try to support my friends, when I can.
And suppose my credit card was not maxed out again, like it frequently is, I would gladly send some cash (so to speak) your way.
Also, it requires a certain maturity for the concept of "you get what you pay for" to evolve. When I was young, I think I bent some car antennas and broke a few windows. I never had to *work* to acquire something. Everything was free, or you saved up for it (with "free" money you got from people, like allowances and christmas, birthdays etc.) so you never really learned the value of something. Sure, you were in love with the new bike you got "yourself" or the stuff you earned by showing up at your grandparents'.
It's been a long, long time (retrospecively) until I realized that just because you
can get something for free does not mean you should. I'm not rich (yet
), and I still pirate songs and music. But at the same time, when I like something I buy the stuff I previously pirated. To relieve my conscience, to support the author/artist AND make my liking show up in the books, so that the author/artist can see, how many fans he has got.