That is a pretty false comparison, and repeatedly trotting it out does weaken your very valid position somewhat.
That lipstick was bought by the shop, and to steal it is to effectively steal its cost price from the shop and, assuming limited stock, deprive the shop of the income from the sale. For an ebook (or any other digital medium) the cost to copy is essentially free, so the loss is that of a potential sale, not the removal of some already extant value.
Were these 'thieves' to not 'steal' David's books, he would be no better off - they would need to be buying those books in addition to not 'stealing' them.
This is not to say that they are somehow right to do what they are doing at all, it's just that it would be nice if we could all stop confusing a breach of copyright law with theft.